assert
The node:assert module provides a set of assertion functions for verifying
invariants.
Indicates the failure of an assertion. All errors thrown by the node:assert module will be instances of the AssertionError class.
Tests for deep equality between the actual and expected parameters.
"Deep" equality means that the enumerable "own" properties of child objects
are recursively evaluated also by the following rules.
Awaits the asyncFn promise or, if asyncFn is a function, immediately
calls the function and awaits the returned promise to complete. It will then
check that the promise is not rejected.
Throws an AssertionError with the provided error message or a default
error message. If the message parameter is an instance of an Error then
it will be thrown instead of the AssertionError.
Throws value if value is not undefined or null. This is useful when
testing the error argument in callbacks. The stack trace contains all frames
from the error passed to ifError() including the potential new frames for ifError() itself.
Tests strict inequality between the actual and expected parameters as
determined by Object.is().
Awaits the asyncFn promise or, if asyncFn is a function, immediately
calls the function and awaits the returned promise to complete. It will then
check that the promise is rejected.
In strict assertion mode, non-strict methods behave like their corresponding strict methods. For example, deepEqual will behave like deepStrictEqual.
Tests strict equality between the actual and expected parameters as
determined by Object.is().
async_hooks
We strongly discourage the use of the async_hooks API.
Other APIs that can cover most of its use cases include:
Resource objects returned by executionAsyncResource() are most often internal
Node.js handle objects with undocumented APIs. Using any functions or properties
on the object is likely to crash your application and should be avoided.
Promise contexts may not get valid triggerAsyncIds by default. See
the section on promise execution tracking.
buffer
Buffer objects are used to represent a fixed-length sequence of bytes. Many
Node.js APIs support Buffers.
Decodes a string of Base64-encoded data into bytes, and encodes those bytes into a string using Latin-1 (ISO-8859-1).
Decodes a string into bytes using Latin-1 (ISO-8859), and encodes those bytes into a string using Base64.
- compare
- copy
- equals
- fill
- includes
- indexOf
- lastIndexOf
- readBigInt64BE
- readBigInt64LE
- readBigUInt64BE
- readBigUInt64LE
- readBigUint64BE
- readBigUint64LE
- readDoubleBE
- readDoubleLE
- readFloatBE
- readFloatLE
- readInt16BE
- readInt16LE
- readInt32BE
- readInt32LE
- readInt8
- readIntBE
- readIntLE
- readUInt16BE
- readUInt16LE
- readUInt32BE
- readUInt32LE
- readUInt8
- readUIntBE
- readUIntLE
- readUint16BE
- readUint16LE
- readUint32BE
- readUint32LE
- readUint8
- readUintBE
- readUintLE
- reverse
- slice
- subarray
- swap16
- swap32
- swap64
- toJSON
- toString
- write
- writeBigInt64BE
- writeBigInt64LE
- writeBigUInt64BE
- writeBigUInt64LE
- writeBigUint64BE
- writeBigUint64LE
- writeDoubleBE
- writeDoubleLE
- writeFloatBE
- writeFloatLE
- writeInt16BE
- writeInt16LE
- writeInt32BE
- writeInt32LE
- writeInt8
- writeIntBE
- writeIntLE
- writeUInt16BE
- writeUInt16LE
- writeUInt32BE
- writeUInt32LE
- writeUInt8
- writeUIntBE
- writeUIntLE
- writeUint16BE
- writeUint16LE
- writeUint32BE
- writeUint32LE
- writeUint8
- writeUintBE
- writeUintLE
Raw data is stored in instances of the Buffer class. A Buffer is similar to an array of integers but corresponds to a raw memory allocation outside the V8 heap. A Buffer cannot be resized. Valid string encodings: 'ascii'|'utf8'|'utf16le'|'ucs2'(alias of 'utf16le')|'base64'|'base64url'|'binary'(deprecated)|'hex'
This function returns true if input contains only valid ASCII-encoded data,
including the case in which input is empty.
This function returns true if input contains only valid UTF-8-encoded data,
including the case in which input is empty.
Resolves a 'blob:nodedata:...' an associated Blob object registered using
a prior call to URL.createObjectURL().
Re-encodes the given Buffer or Uint8Array instance from one character
encoding to another. Returns a new Buffer instance.
Instances of the ChildProcess represent spawned child processes.
The child_process.execFileSync() method is generally identical to execFile with the exception that the method will not
return until the child process has fully closed. When a timeout has been
encountered and killSignal is sent, the method won't return until the process
has completely exited.
The child_process.execSync() method is generally identical to exec with the exception that the method will not return
until the child process has fully closed. When a timeout has been encountered
and killSignal is sent, the method won't return until the process has
completely exited. If the child process intercepts and handles the SIGTERM signal and doesn't exit, the parent process will wait until the child process
has exited.
The child_process.fork() method is a special case of spawn used specifically to spawn new Node.js processes.
Like spawn, a ChildProcess object is returned. The
returned ChildProcess will have an additional communication channel
built-in that allows messages to be passed back and forth between the parent and
child. See subprocess.send() for details.
The child_process.spawn() method spawns a new process using the given command, with command-line arguments in args. If omitted, args defaults
to an empty array.
The child_process.spawnSync() method is generally identical to spawn with the exception that the function will not return
until the child process has fully closed. When a timeout has been encountered
and killSignal is sent, the method won't return until the process has
completely exited. If the process intercepts and handles the SIGTERM signal
and doesn't exit, the parent process will wait until the child process has
exited.
console
The node:console module provides a simple debugging console that is similar to
the JavaScript console mechanism provided by web browsers.
The console module provides a simple debugging console that is similar to the
JavaScript console mechanism provided by web browsers.
crypto
The node:crypto module provides cryptographic functionality that includes a
set of wrappers for OpenSSL's hash, HMAC, cipher, decipher, sign, and verify
functions.
Instances of the Cipher class are used to encrypt data. The class can be
used in one of two ways:
Specifies the active default cipher list used by the current Node.js process (colon-separated values).
Specifies the built-in default cipher list used by Node.js (colon-separated values).
Causes the salt length for RSA_PKCS1_PSS_PADDING to be determined automatically when verifying a signature.
Sets the salt length for RSA_PKCS1_PSS_PADDING to the digest size when signing or verifying.
Sets the salt length for RSA_PKCS1_PSS_PADDING to the maximum permissible value when signing data.
Applies multiple bug workarounds within OpenSSL. See https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html for detail.
Instructs OpenSSL to allow a non-[EC]DHE-based key exchange mode for TLS v1.3
Allows legacy insecure renegotiation between OpenSSL and unpatched clients or servers. See https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html.
Attempts to use the server's preferences instead of the client's when selecting a cipher. See https://www.openssl.org/docs/man1.0.2/ssl/SSL_CTX_set_options.html.
Instructs OpenSSL to use Cisco's version identifier of DTLS_BAD_VER.
Instructs OpenSSL to add server-hello extension from an early version of the cryptopro draft.
Instructs OpenSSL to disable a SSL 3.0/TLS 1.0 vulnerability workaround added in OpenSSL 0.9.6d.
Instructs OpenSSL to always start a new session when performing renegotiation.
Instructs OpenSSL server to prioritize ChaCha20-Poly1305 when the client does. This option has no effect if SSL_OP_CIPHER_SERVER_PREFERENCE is not enabled.
Creates and returns a Cipher object, with the given algorithm, key and
initialization vector (iv).
Creates and returns a Decipher object that uses the given algorithm, key and initialization vector (iv).
Creates a DiffieHellman key exchange object using the supplied prime and an
optional specific generator.
Creates an Elliptic Curve Diffie-Hellman (ECDH) key exchange object using a
predefined curve specified by the curveName string. Use getCurves to obtain a list of available curve names. On recent
OpenSSL releases, openssl ecparam -list_curves will also display the name
and description of each available elliptic curve.
Creates and returns a Hash object that can be used to generate hash digests
using the given algorithm. Optional options argument controls stream
behavior. For XOF hash functions such as 'shake256', the outputLength option
can be used to specify the desired output length in bytes.
Creates and returns an Hmac object that uses the given algorithm and key.
Optional options argument controls stream behavior.
Creates and returns a new key object containing a private key. If key is a
string or Buffer, format is assumed to be 'pem'; otherwise, key must be an object with the properties described above.
Creates and returns a new key object containing a public key. If key is a
string or Buffer, format is assumed to be 'pem'; if key is a KeyObject with type 'private', the public key is derived from the given private key;
otherwise, key must be an object with the properties described above.
Creates and returns a new key object containing a secret key for symmetric
encryption or Hmac.
Creates and returns a Sign object that uses the given algorithm. Use getHashes to obtain the names of the available digest algorithms.
Optional options argument controls the stream.Writable behavior.
Creates and returns a Verify object that uses the given algorithm.
Use getHashes to obtain an array of names of the available
signing algorithms. Optional options argument controls the stream.Writable behavior.
Instances of the Decipher class are used to decrypt data. The class can be
used in one of two ways:
The DiffieHellman class is a utility for creating Diffie-Hellman key
exchanges.
Computes the Diffie-Hellman secret based on a privateKey and a publicKey.
Both keys must have the same asymmetricKeyType, which must be one of 'dh' (for Diffie-Hellman), 'ec' (for ECDH), 'x448', or 'x25519' (for ECDH-ES).
Asynchronously generates a new random secret key of the given length. The type will determine which validations will be performed on the length.
Generates a new asymmetric key pair of the given type. RSA, RSA-PSS, DSA, EC,
Ed25519, Ed448, X25519, X448, and DH are currently supported.
Synchronously generates a new random secret key of the given length. The type will determine which validations will be performed on the length.
Creates a predefined DiffieHellmanGroup key exchange object. The
supported groups are listed in the documentation for DiffieHellmanGroup.
A convenient alias for webcrypto.getRandomValues. This implementation is not compliant with the Web Crypto spec, to write web-compatible code use webcrypto.getRandomValues instead.
A utility for creating one-shot hash digests of data. It can be faster than the object-based crypto.createHash() when hashing a smaller amount of data
(<= 5MB) that's readily available. If the data can be big or if it is streamed, it's still recommended to use crypto.createHash() instead. The algorithm
is dependent on the available algorithms supported by the version of OpenSSL on the platform. Examples are 'sha256', 'sha512', etc. On recent releases
of OpenSSL, openssl list -digest-algorithms will display the available digest algorithms.
HKDF is a simple key derivation function defined in RFC 5869. The given ikm, salt and info are used with the digest to derive a key of keylen bytes.
Provides a synchronous HKDF key derivation function as defined in RFC 5869. The
given ikm, salt and info are used with the digest to derive a key of keylen bytes.
Provides an asynchronous Password-Based Key Derivation Function 2 (PBKDF2)
implementation. A selected HMAC digest algorithm specified by digest is
applied to derive a key of the requested byte length (keylen) from the password, salt and iterations.
Provides a synchronous Password-Based Key Derivation Function 2 (PBKDF2)
implementation. A selected HMAC digest algorithm specified by digest is
applied to derive a key of the requested byte length (keylen) from the password, salt and iterations.
Decrypts buffer with privateKey. buffer was previously encrypted using
the corresponding public key, for example using publicEncrypt.
Encrypts buffer with privateKey. The returned data can be decrypted using
the corresponding public key, for example using publicDecrypt.
Encrypts the content of buffer with key and returns a new Buffer with encrypted content. The returned data can be decrypted using
the corresponding private key, for example using privateDecrypt.
Generates cryptographically strong pseudorandom data. The size argument
is a number indicating the number of bytes to generate.
This function is similar to randomBytes but requires the first
argument to be a Buffer that will be filled. It also
requires that a callback is passed in.
Return a random integer n such that min <= n < max. This
implementation avoids modulo bias.
Generates a random RFC 4122 version 4 UUID. The UUID is generated using a cryptographic pseudorandom number generator.
Provides a synchronous scrypt implementation. Scrypt is a password-based key derivation function that is designed to be expensive computationally and memory-wise in order to make brute-force attacks unrewarding.
Enables the FIPS compliant crypto provider in a FIPS-enabled Node.js build. Throws an error if FIPS mode is not available.
Calculates and returns the signature for data using the given private key and
algorithm. If algorithm is null or undefined, then the algorithm is
dependent upon the key type (especially Ed25519 and Ed448).
This function compares the underlying bytes that represent the given ArrayBuffer, TypedArray, or DataView instances using a constant-time
algorithm.
Verifies the given signature for data using the given key and algorithm. If algorithm is null or undefined, then the algorithm is dependent upon the
key type (especially Ed25519 and Ed448).
Importing the webcrypto object (import { webcrypto } from 'node:crypto') gives an instance of the Crypto class.
Crypto is a singleton that provides access to the remainder of the crypto API.
The CryptoKeyPair is a simple dictionary object with publicKey and privateKey properties, representing an asymmetric key pair.
Encapsulates an X509 certificate and provides read-only access to its information.
dgram
The node:dgram module provides an implementation of UDP datagram sockets.
Creates a dgram.Socket object. Once the socket is created, calling socket.bind() will instruct the socket to begin listening for datagram
messages. When address and port are not passed to socket.bind() the
method will bind the socket to the "all interfaces" address on a random port
(it does the right thing for both udp4 and udp6 sockets). The bound address
and port can be retrieved using socket.address().address and socket.address().port.
- addListener
- addMembership
- addSourceSpecificMembership
- address
- bind
- close
- connect
- disconnect
- dropMembership
- dropSourceSpecificMembership
- emit
- getRecvBufferSize
- getSendBufferSize
- getSendQueueCount
- getSendQueueSize
- on
- once
- prependListener
- prependOnceListener
- ref
- remoteAddress
- send
- setBroadcast
- setMulticastInterface
- setMulticastLoopback
- setMulticastTTL
- setRecvBufferSize
- setSendBufferSize
- setTTL
- unref
diagnostics_channel
The node:diagnostics_channel module provides an API to create named channels
to report arbitrary message data for diagnostics purposes.
The class Channel represents an individual named channel within the data
pipeline. It is used to track subscribers and to publish messages when there
are subscribers present. It exists as a separate object to avoid channel
lookups at publish time, enabling very fast publish speeds and allowing
for heavy use while incurring very minimal cost. Channels are created with channel, constructing a channel directly
with new Channel(name) is not supported.
This is the primary entry-point for anyone wanting to publish to a named channel. It produces a channel object which is optimized to reduce overhead at publish time as much as possible.
Check if there are active subscribers to the named channel. This is helpful if the message you want to send might be expensive to prepare.
Register a message handler to subscribe to this channel. This message handler
will be run synchronously whenever a message is published to the channel. Any
errors thrown in the message handler will trigger an 'uncaughtException'.
The class TracingChannel is a collection of TracingChannel Channels which
together express a single traceable action. It is used to formalize and
simplify the process of producing events for tracing application flow. tracingChannel is used to construct a TracingChannel. As with Channel it is recommended to create and reuse a
single TracingChannel at the top-level of the file rather than creating them
dynamically.
Creates a TracingChannel wrapper for the given TracingChannel Channels. If a name is given, the corresponding tracing
channels will be created in the form of tracing:${name}:${eventType} where eventType corresponds to the types of TracingChannel Channels.
dns
The node:dns module enables name resolution. For example, use it to look up IP
addresses of host names.
Limits returned address types to the types of non-loopback addresses configured on the system. For example, IPv4 addresses are only returned if the current system has at least one IPv4 address configured.
If dns.V4MAPPED is specified, return resolved IPv6 addresses as
well as IPv4 mapped IPv6 addresses.
Get the default value for order in lookup and dnsPromises.lookup().
The value could be:
Returns an array of IP address strings, formatted according to RFC 5952, that are currently configured for DNS resolution. A string will include a port section if a custom port is used.
Resolves a host name (e.g. 'nodejs.org') into the first found A (IPv4) or
AAAA (IPv6) record. All option properties are optional. If options is an
integer, then it must be 4 or 6 – if options is 0 or not provided, then
IPv4 and IPv6 addresses are both returned if found.
Resolves the given address and port into a host name and service using
the operating system's underlying getnameinfo implementation.
The dns.promises API provides an alternative set of asynchronous DNS methods
that return Promise objects rather than using callbacks. The API is accessible
via import { promises as dnsPromises } from 'node:dns' or import dnsPromises from 'node:dns/promises'.
Performs a reverse DNS query that resolves an IPv4 or IPv6 address to an array of host names.
Set the default value of order in lookup and dnsPromises.lookup().
The value could be:
Sets the IP address and port of servers to be used when performing DNS
resolution. The servers argument is an array of RFC 5952 formatted
addresses. If the port is the IANA default DNS port (53) it can be omitted.
If the IPv6 family was specified, but no IPv6 addresses were found, then return IPv4 mapped IPv6 addresses. It is not supported on some operating systems (e.g. FreeBSD 10.1).
dns/promises
The dns.promises API provides an alternative set of asynchronous DNS methods
that return Promise objects rather than using callbacks. The API is accessible
via import { promises as dnsPromises } from 'node:dns' or import dnsPromises from 'node:dns/promises'.
Get the default value for verbatim in lookup and dnsPromises.lookup().
The value could be:
Returns an array of IP address strings, formatted according to RFC 5952, that are currently configured for DNS resolution. A string will include a port section if a custom port is used.
Resolves a host name (e.g. 'nodejs.org') into the first found A (IPv4) or
AAAA (IPv6) record. All option properties are optional. If options is an
integer, then it must be 4 or 6 – if options is not provided, then IPv4
and IPv6 addresses are both returned if found.
Resolves the given address and port into a host name and service using
the operating system's underlying getnameinfo implementation.
Get the default value for verbatim in lookup and dnsPromises.lookup().
The value could be:
Returns an array of IP address strings, formatted according to RFC 5952, that are currently configured for DNS resolution. A string will include a port section if a custom port is used.
Resolves a host name (e.g. 'nodejs.org') into the first found A (IPv4) or
AAAA (IPv6) record. All option properties are optional. If options is an
integer, then it must be 4 or 6 – if options is not provided, then IPv4
and IPv6 addresses are both returned if found.
Resolves the given address and port into a host name and service using
the operating system's underlying getnameinfo implementation.
Uses the DNS protocol to resolve a host name (e.g. 'nodejs.org') into an array
of the resource records. When successful, the Promise is resolved with an
array of resource records. The type and structure of individual results vary
based on rrtype:
Uses the DNS protocol to resolve IPv4 addresses (A records) for the hostname. On success, the Promise is resolved with an array of IPv4
addresses (e.g. ['74.125.79.104', '74.125.79.105', '74.125.79.106']).
Uses the DNS protocol to resolve IPv6 addresses (AAAA records) for the hostname. On success, the Promise is resolved with an array of IPv6
addresses.
Uses the DNS protocol to resolve all records (also known as ANY or * query).
On success, the Promise is resolved with an array containing various types of
records. Each object has a property type that indicates the type of the
current record. And depending on the type, additional properties will be
present on the object:
Uses the DNS protocol to resolve CAA records for the hostname. On success,
the Promise is resolved with an array of objects containing available
certification authority authorization records available for the hostname (e.g. [{critical: 0, iodef: 'mailto:pki@example.com'},{critical: 128, issue: 'pki.example.com'}]).
Uses the DNS protocol to resolve CNAME records for the hostname. On success,
the Promise is resolved with an array of canonical name records available for
the hostname (e.g. ['bar.example.com']).
Uses the DNS protocol to resolve mail exchange records (MX records) for the hostname. On success, the Promise is resolved with an array of objects
containing both a priority and exchange property (e.g.[{priority: 10, exchange: 'mx.example.com'}, ...]).
Uses the DNS protocol to resolve regular expression-based records (NAPTR records) for the hostname. On success, the Promise is resolved with an array
of objects with the following properties:
Uses the DNS protocol to resolve name server records (NS records) for the hostname. On success, the Promise is resolved with an array of name server
records available for hostname (e.g.['ns1.example.com', 'ns2.example.com']).
Uses the DNS protocol to resolve pointer records (PTR records) for the hostname. On success, the Promise is resolved with an array of strings
containing the reply records.
Uses the DNS protocol to resolve a start of authority record (SOA record) for
the hostname. On success, the Promise is resolved with an object with the
following properties:
Uses the DNS protocol to resolve service records (SRV records) for the hostname. On success, the Promise is resolved with an array of objects with
the following properties:
Uses the DNS protocol to resolve text queries (TXT records) for the hostname. On success, the Promise is resolved with a two-dimensional array
of the text records available for hostname (e.g.[ ['v=spf1 ip4:0.0.0.0 ', '~all' ] ]). Each sub-array contains TXT chunks of
one record. Depending on the use case, these could be either joined together or
treated separately.
Performs a reverse DNS query that resolves an IPv4 or IPv6 address to an array of host names.
Set the default value of order in dns.lookup() and [lookup](././dns/promises/~/lookup). The value could be:
Sets the IP address and port of servers to be used when performing DNS
resolution. The servers argument is an array of RFC 5952 formatted
addresses. If the port is the IANA default DNS port (53) it can be omitted.
Uses the DNS protocol to resolve a host name (e.g. 'nodejs.org') into an array
of the resource records. When successful, the Promise is resolved with an
array of resource records. The type and structure of individual results vary
based on rrtype:
Uses the DNS protocol to resolve IPv4 addresses (A records) for the hostname. On success, the Promise is resolved with an array of IPv4
addresses (e.g. ['74.125.79.104', '74.125.79.105', '74.125.79.106']).
Uses the DNS protocol to resolve IPv6 addresses (AAAA records) for the hostname. On success, the Promise is resolved with an array of IPv6
addresses.
Uses the DNS protocol to resolve all records (also known as ANY or * query).
On success, the Promise is resolved with an array containing various types of
records. Each object has a property type that indicates the type of the
current record. And depending on the type, additional properties will be
present on the object:
Uses the DNS protocol to resolve CAA records for the hostname. On success,
the Promise is resolved with an array of objects containing available
certification authority authorization records available for the hostname (e.g. [{critical: 0, iodef: 'mailto:pki@example.com'},{critical: 128, issue: 'pki.example.com'}]).
Uses the DNS protocol to resolve CNAME records for the hostname. On success,
the Promise is resolved with an array of canonical name records available for
the hostname (e.g. ['bar.example.com']).
Uses the DNS protocol to resolve mail exchange records (MX records) for the hostname. On success, the Promise is resolved with an array of objects
containing both a priority and exchange property (e.g.[{priority: 10, exchange: 'mx.example.com'}, ...]).
Uses the DNS protocol to resolve regular expression-based records (NAPTR records) for the hostname. On success, the Promise is resolved with an array
of objects with the following properties:
Uses the DNS protocol to resolve name server records (NS records) for the hostname. On success, the Promise is resolved with an array of name server
records available for hostname (e.g.['ns1.example.com', 'ns2.example.com']).
Uses the DNS protocol to resolve pointer records (PTR records) for the hostname. On success, the Promise is resolved with an array of strings
containing the reply records.
Uses the DNS protocol to resolve a start of authority record (SOA record) for
the hostname. On success, the Promise is resolved with an object with the
following properties:
Uses the DNS protocol to resolve service records (SRV records) for the hostname. On success, the Promise is resolved with an array of objects with
the following properties:
Uses the DNS protocol to resolve text queries (TXT records) for the hostname. On success, the Promise is resolved with a two-dimensional array
of the text records available for hostname (e.g.[ ['v=spf1 ip4:0.0.0.0 ', '~all' ] ]). Each sub-array contains TXT chunks of
one record. Depending on the use case, these could be either joined together or
treated separately.
Performs a reverse DNS query that resolves an IPv4 or IPv6 address to an array of host names.
Set the default value of order in dns.lookup() and [lookup](././dns/promises/~/lookup). The value could be:
Sets the IP address and port of servers to be used when performing DNS
resolution. The servers argument is an array of RFC 5952 formatted
addresses. If the port is the IANA default DNS port (53) it can be omitted.
events
Much of the Node.js core API is built around an idiomatic asynchronous
event-driven architecture in which certain kinds of objects (called "emitters")
emit named events that cause Function objects ("listeners") to be called.
The EventEmitter class is defined and exposed by the node:events module:
Integrates EventEmitter with AsyncResource for EventEmitters that
require manual async tracking. Specifically, all events emitted by instances
of events.EventEmitterAsyncResource will run within its async context.
fs
The node:fs module enables interacting with the file system in a
way modeled on standard POSIX functions.
Tests a user's permissions for the file or directory specified by path.
The mode argument is an optional integer that specifies the accessibility
checks to be performed. mode should be either the value fs.constants.F_OK or a mask consisting of the bitwise OR of any of fs.constants.R_OK, fs.constants.W_OK, and fs.constants.X_OK
(e.g.fs.constants.W_OK | fs.constants.R_OK). Check File access constants for
possible values of mode.
Synchronously tests a user's permissions for the file or directory specified
by path. The mode argument is an optional integer that specifies the
accessibility checks to be performed. mode should be either the value fs.constants.F_OK or a mask consisting of the bitwise OR of any of fs.constants.R_OK, fs.constants.W_OK, and
fs.constants.X_OK (e.g.fs.constants.W_OK | fs.constants.R_OK). Check File access constants for
possible values of mode.
Asynchronously append data to a file, creating the file if it does not yet
exist. data can be a string or a Buffer.
Synchronously append data to a file, creating the file if it does not yet
exist. data can be a string or a Buffer.
Asynchronously changes the permissions of a file. No arguments other than a possible exception are given to the completion callback.
Asynchronously changes owner and group of a file. No arguments other than a possible exception are given to the completion callback.
Closes the file descriptor. No arguments other than a possible exception are given to the completion callback.
Constant for fs.copyFile. Flag indicating the destination file should not be overwritten if it already exists.
Constant for fs.copyFile. copy operation will attempt to create a copy-on-write reflink. If the underlying platform does not support copy-on-write, then a fallback copy mechanism is used.
Constant for fs.copyFile. Copy operation will attempt to create a copy-on-write reflink. If the underlying platform does not support copy-on-write, then the operation will fail with an error.
Constant for fs.open(). Flag indicating that data will be appended to the end of the file.
Constant for fs.open(). Flag indicating to create the file if it does not already exist.
Constant for fs.open(). When set, an attempt will be made to minimize caching effects of file I/O.
Constant for fs.open(). Flag indicating that the open should fail if the path is not a directory.
Constant for fs.open(). Flag indicating that the file is opened for synchronous I/O with write operations waiting for data integrity.
Constant for fs.open(). Flag indicating that opening a file should fail if the O_CREAT flag is set and the file already exists.
constant for fs.open(). Flag indicating reading accesses to the file system will no longer result in an update to the atime information associated with the file. This flag is available on Linux operating systems only.
Constant for fs.open(). Flag indicating that if path identifies a terminal device, opening the path shall not cause that terminal to become the controlling terminal for the process (if the process does not already have one).
Constant for fs.open(). Flag indicating that the open should fail if the path is a symbolic link.
Constant for fs.open(). Flag indicating to open the file in nonblocking mode when possible.
Constant for fs.open(). Flag indicating to open the symbolic link itself rather than the resource it is pointing to.
Constant for fs.open(). Flag indicating that the file is opened for synchronous I/O.
Constant for fs.open(). Flag indicating that if the file exists and is a regular file, and the file is opened successfully for write access, its length shall be truncated to zero.
Constant for fs.Stats mode property for determining a file's type. File type constant for a block-oriented device file.
Constant for fs.Stats mode property for determining a file's type. File type constant for a character-oriented device file.
Constant for fs.Stats mode property for determining a file's type. File type constant for a directory.
Constant for fs.Stats mode property for determining a file's type. File type constant for a FIFO/pipe.
Constant for fs.Stats mode property for determining a file's type. File type constant for a symbolic link.
Constant for fs.Stats mode property for determining a file's type. Bit mask used to extract the file type code.
Constant for fs.Stats mode property for determining a file's type. File type constant for a regular file.
Constant for fs.Stats mode property for determining a file's type. File type constant for a socket.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating readable by group.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating readable by others.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating readable by owner.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating readable, writable and executable by group.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating readable, writable and executable by others.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating readable, writable and executable by owner.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating writable by group.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating writable by others.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating writable by owner.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating executable by group.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating executable by others.
Constant for fs.Stats mode property for determining access permissions for a file. File mode indicating executable by owner.
When set, a memory file mapping is used to access the file. This flag is available on Windows operating systems only. On other operating systems, this flag is ignored.
Asynchronously copies src to dest. By default, dest is overwritten if it
already exists. No arguments other than a possible exception are given to the
callback function. Node.js makes no guarantees about the atomicity of the copy
operation. If an error occurs after the destination file has been opened for
writing, Node.js will attempt to remove the destination.
Synchronously copies src to dest. By default, dest is overwritten if it
already exists. Returns undefined. Node.js makes no guarantees about the
atomicity of the copy operation. If an error occurs after the destination file
has been opened for writing, Node.js will attempt to remove the destination.
Asynchronously copies the entire directory structure from src to dest,
including subdirectories and files.
Synchronously copies the entire directory structure from src to dest,
including subdirectories and files.
Unlike the 16 KiB default highWaterMark for a stream.Readable, the stream
returned by this method has a default highWaterMark of 64 KiB.
options may also include a start option to allow writing data at some
position past the beginning of the file, allowed values are in the
[0, Number.MAX_SAFE_INTEGER] range. Modifying a file rather than
replacing it may require the flags option to be set to r+ rather than the
default w. The encoding can be any one of those accepted by Buffer.
A representation of a directory entry, which can be a file or a subdirectory
within the directory, as returned by reading from an fs.Dir. The
directory entry is a combination of the file name and file type pairs.
Sets the permissions on the file. No arguments other than a possible exception are given to the completion callback.
Sets the owner of the file. No arguments other than a possible exception are given to the completion callback.
Forces all currently queued I/O operations associated with the file to the
operating system's synchronized I/O completion state. Refer to the POSIX fdatasync(2) documentation for details. No arguments other
than a possible
exception are given to the completion callback.
Forces all currently queued I/O operations associated with the file to the
operating system's synchronized I/O completion state. Refer to the POSIX fdatasync(2) documentation for details. Returns undefined.
Request that all data for the open file descriptor is flushed to the storage
device. The specific implementation is operating system and device specific.
Refer to the POSIX fsync(2) documentation for more detail. No arguments other
than a possible exception are given to the completion callback.
Truncates the file descriptor. No arguments other than a possible exception are given to the completion callback.
Set the owner of the symbolic link. No arguments other than a possible exception are given to the completion callback.
Retrieves the fs.Stats for the symbolic link referred to by the path.
The callback gets two arguments (err, stats) where stats is a fs.Stats object. lstat() is identical to stat(), except that if path is a symbolic
link, then the link itself is stat-ed, not the file that it refers to.
Change the file system timestamps of the symbolic link referenced by path.
Returns undefined, or throws an exception when parameters are incorrect or
the operation fails. This is the synchronous version of lutimes.
Reads the contents of a directory. The callback gets two arguments (err, files) where files is an array of the names of the files in the directory excluding '.' and '..'.
Reads the contents of the symbolic link referred to by path. The callback gets
two arguments (err, linkString).
Instances of fs.ReadStream are created and returned using the createReadStream function.
Asynchronously rename file at oldPath to the pathname provided
as newPath. In the case that newPath already exists, it will
be overwritten. If there is a directory at newPath, an error will
be raised instead. No arguments other than a possible exception are
given to the completion callback.
Asynchronously removes files and directories (modeled on the standard POSIX rm utility). No arguments other than a possible exception are given to the
completion callback.
Synchronously removes files and directories (modeled on the standard POSIX rm utility). Returns undefined.
Synchronous statfs(2). Returns information about the mounted file system which
contains path.
Creates the link called path pointing to target. No arguments other than a
possible exception are given to the completion callback.
Truncates the file. No arguments other than a possible exception are
given to the completion callback. A file descriptor can also be passed as the
first argument. In this case, fs.ftruncate() is called.
Truncates the file. Returns undefined. A file descriptor can also be
passed as the first argument. In this case, fs.ftruncateSync() is called.
Asynchronously removes a file or symbolic link. No arguments other than a possible exception are given to the completion callback.
Stop watching for changes on filename. If listener is specified, only that
particular listener is removed. Otherwise, all listeners are removed,
effectively stopping watching of filename.
Watch for changes on filename. The callback listener will be called each
time the file is accessed.
Watch for changes on filename. The callback listener will be called each
time the file is accessed.
stream.WritableFor detailed information, see the documentation of the asynchronous version of this API: writev.
Test whether or not the given path exists by checking with the file system.
Then call the callback argument with either true or false:
Changes the permissions on a symbolic link. No arguments other than a possible exception are given to the completion callback.
fs/promises
The fs/promises API provides asynchronous file system methods that return
promises.
Tests a user's permissions for the file or directory specified by path.
The mode argument is an optional integer that specifies the accessibility
checks to be performed. mode should be either the value fs.constants.F_OK or a mask consisting of the bitwise OR of any of fs.constants.R_OK, fs.constants.W_OK, and fs.constants.X_OK
(e.g.fs.constants.W_OK | fs.constants.R_OK). Check File access constants for
possible values of mode.
Asynchronously append data to a file, creating the file if it does not yet
exist. data can be a string or a Buffer.
Asynchronously copies the entire directory structure from src to dest,
including subdirectories and files.
Changes the access and modification times of a file in the same way as fsPromises.utimes(), with the difference that if the path refers to a
symbolic link, then the link is not dereferenced: instead, the timestamps of
the symbolic link itself are changed.
Creates a unique temporary directory. A unique directory name is generated by
appending six random characters to the end of the provided prefix. Due to
platform inconsistencies, avoid trailing X characters in prefix. Some
platforms, notably the BSDs, can return more than six random characters, and
replace trailing X characters in prefix with random characters.
Asynchronously open a directory for iterative scanning. See the POSIX opendir(3) documentation for more detail.
Tests a user's permissions for the file or directory specified by path.
The mode argument is an optional integer that specifies the accessibility
checks to be performed. mode should be either the value fs.constants.F_OK or a mask consisting of the bitwise OR of any of fs.constants.R_OK, fs.constants.W_OK, and fs.constants.X_OK
(e.g.fs.constants.W_OK | fs.constants.R_OK). Check File access constants for
possible values of mode.
Asynchronously append data to a file, creating the file if it does not yet
exist. data can be a string or a Buffer.
Asynchronously copies src to dest. By default, dest is overwritten if it
already exists.
Asynchronously copies the entire directory structure from src to dest,
including subdirectories and files.
Creates a new link from the existingPath to the newPath. See the POSIX link(2) documentation for more detail.
Equivalent to fsPromises.stat() unless path refers to a symbolic link,
in which case the link itself is stat-ed, not the file that it refers to.
Refer to the POSIX lstat(2) document for more detail.
Changes the access and modification times of a file in the same way as fsPromises.utimes(), with the difference that if the path refers to a
symbolic link, then the link is not dereferenced: instead, the timestamps of
the symbolic link itself are changed.
Creates a unique temporary directory. A unique directory name is generated by
appending six random characters to the end of the provided prefix. Due to
platform inconsistencies, avoid trailing X characters in prefix. Some
platforms, notably the BSDs, can return more than six random characters, and
replace trailing X characters in prefix with random characters.
Asynchronously open a directory for iterative scanning. See the POSIX opendir(3) documentation for more detail.
Reads the contents of the symbolic link referred to by path. See the POSIX readlink(2) documentation for more detail. The promise is
fulfilled with thelinkString upon success.
Determines the actual location of path using the same semantics as the fs.realpath.native() function.
If path refers to a symbolic link, then the link is removed without affecting
the file or directory to which that link refers. If the path refers to a file
path that is not a symbolic link, the file is deleted. See the POSIX unlink(2) documentation for more detail.
Returns an async iterator that watches for changes on filename, where filenameis either a file or a directory.
Asynchronously writes data to a file, replacing the file if it already exists. data can be a string, a buffer, an
AsyncIterable, or an
Iterable object.
Reads the contents of the symbolic link referred to by path. See the POSIX readlink(2) documentation for more detail. The promise is
fulfilled with thelinkString upon success.
Determines the actual location of path using the same semantics as the fs.realpath.native() function.
Returns an async iterator that watches for changes on filename, where filenameis either a file or a directory.
Asynchronously writes data to a file, replacing the file if it already exists. data can be a string, a buffer, an
AsyncIterable, or an
Iterable object.
http
To use the HTTP server and client one must import the node:http module.
An Agent is responsible for managing connection persistence
and reuse for HTTP clients. It maintains a queue of pending requests
for a given host and port, reusing a single socket connection for each
until the queue is empty, at which time the socket is either destroyed
or put into a pool where it is kept to be used again for requests to the
same host and port. Whether it is destroyed or pooled depends on the keepAlive option.
Global instance of Agent which is used as the default for all HTTP client
requests. Diverges from a default Agent configuration by having keepAlive
enabled and a timeout of 5 seconds.
- accept
- accept-language
- accept-patch
- accept-ranges
- access-control-allow-credentials
- access-control-allow-headers
- access-control-allow-methods
- access-control-allow-origin
- access-control-expose-headers
- access-control-max-age
- access-control-request-headers
- access-control-request-method
- age
- allow
- alt-svc
- authorization
- cache-control
- connection
- content-disposition
- content-encoding
- content-language
- content-length
- content-location
- content-range
- content-type
- cookie
- date
- etag
- expect
- expires
- forwarded
- from
- host
- if-match
- if-modified-since
- if-none-match
- if-unmodified-since
- last-modified
- location
- origin
- pragma
- proxy-authenticate
- proxy-authorization
- public-key-pins
- range
- referer
- retry-after
- sec-websocket-accept
- sec-websocket-extensions
- sec-websocket-key
- sec-websocket-protocol
- sec-websocket-version
- set-cookie
- strict-transport-security
- tk
- trailer
- transfer-encoding
- upgrade
- user-agent
- vary
- via
- warning
- www-authenticate
An IncomingMessage object is created by Server or ClientRequest and passed as the first argument to the 'request' and 'response' event respectively. It may be used to
access response
status, headers, and data.
Read-only property specifying the maximum allowed size of HTTP headers in bytes.
Defaults to 16KB. Configurable using the --max-http-header-size CLI option.
- accept
- accept-charset
- accept-encoding
- accept-language
- accept-ranges
- access-control-allow-credentials
- access-control-allow-headers
- access-control-allow-methods
- access-control-allow-origin
- access-control-expose-headers
- access-control-max-age
- access-control-request-headers
- access-control-request-method
- age
- allow
- authorization
- cache-control
- cdn-cache-control
- connection
- content-disposition
- content-encoding
- content-language
- content-length
- content-location
- content-range
- content-security-policy
- content-security-policy-report-only
- cookie
- date
- dav
- dnt
- etag
- expect
- expires
- forwarded
- from
- host
- if-match
- if-modified-since
- if-none-match
- if-range
- if-unmodified-since
- last-modified
- link
- location
- max-forwards
- origin
- prgama
- proxy-authenticate
- proxy-authorization
- public-key-pins
- public-key-pins-report-only
- range
- referer
- referrer-policy
- refresh
- retry-after
- sec-websocket-accept
- sec-websocket-extensions
- sec-websocket-key
- sec-websocket-protocol
- sec-websocket-version
- server
- set-cookie
- strict-transport-security
- te
- trailer
- transfer-encoding
- upgrade
- upgrade-insecure-requests
- user-agent
- vary
- via
- warning
- www-authenticate
- x-content-type-options
- x-dns-prefetch-control
- x-frame-options
- x-xss-protection
This class serves as the parent class of ClientRequest and ServerResponse. It is an abstract outgoing message from the perspective of the participants of an HTTP transaction.
This object is created internally by an HTTP server, not by the user. It is
passed as the second parameter to the 'request' event.
Performs the low-level validations on the provided name that are done when res.setHeader(name, value) is called.
Performs the low-level validations on the provided value that are done when res.setHeader(name, value) is called.
http2
The node:http2 module provides an implementation of the HTTP/2 protocol.
It can be accessed using:
A Http2ServerRequest object is created by Server or SecureServer and passed as the first argument to the 'request' event. It may be used to access a request status,
headers, and
data.
This object is created internally by an HTTP server, not by the user. It is
passed as the second parameter to the 'request' event.
This symbol can be set as a property on the HTTP/2 headers object with an array value in order to provide a list of headers considered sensitive.
https
HTTPS is the HTTP protocol over TLS/SSL. In Node.js this is implemented as a separate module.
JavaScript call frame. Array of call frames form the call stack.
Sampling Heap Profile node. Holds callsite information, allocation statistics and child nodes.
This feature is only available with the --experimental-network-inspection flag enabled.
This feature is only available with the --experimental-network-inspection flag enabled.
This feature is only available with the --experimental-network-inspection flag enabled.
This feature is only available with the --experimental-network-inspection flag enabled.
Activate inspector on host and port. Equivalent to node --inspect=[[host:]port], but can be done programmatically after node has
started.
Specifies a number of samples attributed to a certain source position.
Profile node. Holds callsite information, execution statistics and child nodes.
Represents function call argument. Either remote object id objectId, primitive value, unserializable primitive value or neither of (for undefined) them should be specified.
Stack entry for runtime errors and assertions.
Detailed information about exception (or error) that was thrown during script compilation or execution.
Object internal property descriptor. This property isn't normally visible in JavaScript code.
Object containing abbreviated remote object value.
Object property descriptor.
Mirror object referencing original JavaScript object.
If debuggerId is set stack trace comes from another debugger and can be resolved there. This allows to track cross-debugger calls. See Runtime.StackTrace and Debugger.paused for usages.
The inspector.Session is used for dispatching messages to the V8 inspector
back-end and receiving message responses and notifications.
Blocks until a client (existing or connected later) has sent Runtime.runIfWaitingForDebugger command.
inspector/promises
The node:inspector/promises module provides an API for interacting with the V8
inspector.
JavaScript call frame. Array of call frames form the call stack.
Sampling Heap Profile node. Holds callsite information, allocation statistics and child nodes.
This feature is only available with the --experimental-network-inspection flag enabled.
This feature is only available with the --experimental-network-inspection flag enabled.
This feature is only available with the --experimental-network-inspection flag enabled.
This feature is only available with the --experimental-network-inspection flag enabled.
Specifies a number of samples attributed to a certain source position.
Profile node. Holds callsite information, execution statistics and child nodes.
Represents function call argument. Either remote object id objectId, primitive value, unserializable primitive value or neither of (for undefined) them should be specified.
Stack entry for runtime errors and assertions.
Detailed information about exception (or error) that was thrown during script compilation or execution.
Object internal property descriptor. This property isn't normally visible in JavaScript code.
Object containing abbreviated remote object value.
Object property descriptor.
Mirror object referencing original JavaScript object.
If debuggerId is set stack trace comes from another debugger and can be resolved there. This allows to track cross-debugger calls. See Runtime.StackTrace and Debugger.paused for usages.
The inspector.Session is used for dispatching messages to the V8 inspector
back-end and receiving message responses and notifications.
path is the resolved path for the file for which a corresponding source map
should be fetched.
The initialize hook provides a way to define a custom function that runs in the hooks thread
when the hooks module is initialized. Initialization happens when the hooks module is registered via register.
The load hook provides a way to define a custom method of determining how a URL should be interpreted, retrieved, and parsed.
It is also in charge of validating the import assertion.
The resolve hook chain is responsible for resolving file URL for a given module specifier and parent URL, and optionally its format (such as 'module') as a hint to the load hook.
If a format is specified, the load hook is ultimately responsible for providing the final format value (and it is free to ignore the hint provided by resolve);
if resolve provides a format, a custom load hook is required even if only to pass the value to the Node.js default load hook.
The module.syncBuiltinESMExports() method updates all the live bindings for
builtin ES Modules to match the properties of the CommonJS exports. It
does not add or remove exported names from the ES Modules.
net
Stability: 2 - Stable
A factory function, which creates a new Socket,
immediately initiates connection with socket.connect(),
then returns the net.Socket that starts the connection.
Gets the current default value of the autoSelectFamily option of socket.connect(options).
The initial default value is true, unless the command line option--no-network-family-autoselection is provided.
Gets the current default value of the autoSelectFamilyAttemptTimeout option of socket.connect(options).
The initial default value is 250 or the value specified via the command line option --network-family-autoselection-attempt-timeout.
Returns 6 if input is an IPv6 address. Returns 4 if input is an IPv4
address in dot-decimal notation with no leading zeroes. Otherwise, returns0.
Returns true if input is an IPv4 address in dot-decimal notation with no
leading zeroes. Otherwise, returns false.
This class is used to create a TCP or IPC server.
Sets the default value of the autoSelectFamily option of socket.connect(options).
Sets the default value of the autoSelectFamilyAttemptTimeout option of socket.connect(options).
- addListener
- address
- autoSelectFamilyAttemptedAddresses
- bufferSize
- bytesRead
- bytesWritten
- connect
- connecting
- destroySoon
- destroyed
- emit
- end
- localAddress
- localFamily
- localPort
- on
- once
- pause
- pending
- prependListener
- prependOnceListener
- readyState
- ref
- remoteAddress
- remoteFamily
- remotePort
- resetAndDestroy
- resume
- setEncoding
- setKeepAlive
- setNoDelay
- setTimeout
- timeout
- unref
- write
os
The node:os module provides operating system-related utility methods and
properties. It can be accessed using:
Returns the operating system CPU architecture for which the Node.js binary was
compiled. Possible values are 'arm', 'arm64', 'ia32', 'loong64', 'mips', 'mipsel', 'ppc', 'ppc64', 'riscv64', 's390', 's390x',
and 'x64'.
Returns an estimate of the default amount of parallelism a program should use. Always returns a value greater than zero.
Returns an array of objects containing information about each logical CPU core.
The array will be empty if no CPU information is available, such as if the /proc file system is unavailable.
Returns a string identifying the endianness of the CPU for which the Node.js binary was compiled.
Returns the scheduling priority for the process specified by pid. If pid is
not provided or is 0, the priority of the current process is returned.
Returns the machine type as a string, such as arm, arm64, aarch64, mips, mips64, ppc64, ppc64le, s390, s390x, i386, i686, x86_64.
Returns an object containing network interfaces that have been assigned a network address.
Returns a string identifying the operating system platform for which
the Node.js binary was compiled. The value is set at compile time.
Possible values are 'aix', 'darwin', 'freebsd', 'linux', 'openbsd', 'sunos', and 'win32'.
Attempts to set the scheduling priority for the process specified by pid. If pid is not provided or is 0, the process ID of the current process is used.
Returns information about the currently effective user. On POSIX platforms,
this is typically a subset of the password file. The returned object includes
the username, uid, gid, shell, and homedir. On Windows, the uid and gid fields are -1, and shell is null.
path
The node:path module provides utilities for working with file and directory
paths. It can be accessed using:
perf_hooks
This module provides an implementation of a subset of the W3C Web Performance APIs as well as additional APIs for Node.js-specific performance measurements.
This property is an extension by Node.js. It is not available in Web browsers.
Provides detailed network timing data regarding the loading of an application's resources.
- abort
- addListener
- allowedNodeEnvironmentFlags
- arch
- argv
- argv0
- availableMemory
- channel
- chdir
- config
- connected
- constrainedMemory
- cpuUsage
- cwd
- debugPort
- disconnect
- dlopen
- emit
- emitWarning
- env
- execArgv
- execPath
- exit
- exitCode
- features
- finalization
- getActiveResourcesInfo
- getBuiltinModule
- getegid
- geteuid
- getgid
- getgroups
- getuid
- hasUncaughtExceptionCaptureCallback
- hrtime
- kill
- listeners
- loadEnvFile
- mainModule
- memoryUsage
- nextTick
- on
- once
- permission
- pid
- platform
- ppid
- prependListener
- prependOnceListener
- release
- report
- resourceUsage
- send
- setSourceMapsEnabled
- setUncaughtExceptionCaptureCallback
- setegid
- seteuid
- setgid
- setgroups
- setuid
- sourceMapsEnabled
- stderr
- stdin
- stdout
- throwDeprecation
- title
- traceDeprecation
- umask
- uptime
- version
- versions
Most of the time the unhandledRejection will be an Error, but this should not be relied upon as anything can be thrown/rejected, it is therefore unsafe to assume that the value is an Error.
punycode
**The version of the punycode module bundled in Node.js is being deprecated. **In a future major version of Node.js this module will be removed. Users
currently depending on the punycode module should switch to using the
userland-provided Punycode.js module instead. For punycode-based URL
encoding, see url.domainToASCII or, more generally, the WHATWG URL API.
querystring
The node:querystring module provides utilities for parsing and formatting URL
query strings. It can be accessed using:
The querystring.escape() method performs URL percent-encoding on the given str in a manner that is optimized for the specific requirements of URL
query strings.
The querystring.parse() method parses a URL query string (str) into a
collection of key and value pairs.
The querystring.stringify() method produces a URL query string from a
given obj by iterating through the object's "own properties".
The node:querystring module provides utilities for parsing and formatting URL
query strings. It can be accessed using:
The querystring.unescape() method performs decoding of URL percent-encoded
characters on the given str.
readline
The node:readline module provides an interface for reading data from a Readable stream
(such as process.stdin) one line at a time.
The readline.clearScreenDown() method clears the given TTY stream from
the current position of the cursor down.
The readline.emitKeypressEvents() method causes the given Readable stream to begin emitting 'keypress' events corresponding to received input.
Instances of the readline.Interface class are constructed using the readline.createInterface() method. Every instance is associated with a
single input Readable stream and a single output Writable stream.
The output stream is used to print prompts for user input that arrives on,
and is read from, the input stream.
The readline.moveCursor() method moves the cursor relative to its current
position in a given TTY stream.
The readlinePromises.createInterface() method creates a new readlinePromises.Interface instance.
Instances of the readlinePromises.Interface class are constructed using the readlinePromises.createInterface() method. Every instance is associated with a
single input Readable stream and a single output Writable stream.
The output stream is used to print prompts for user input that arrives on,
and is read from, the input stream.
The readlinePromises.createInterface() method creates a new readlinePromises.Interface instance.
Instances of the readlinePromises.Interface class are constructed using the readlinePromises.createInterface() method. Every instance is associated with a
single input Readable stream and a single output Writable stream.
The output stream is used to print prompts for user input that arrives on,
and is read from, the input stream.
A flag passed in the REPL options. Evaluates expressions in strict mode.
This is equivalent to prefacing every repl statement with 'use strict'.
This is the default "writer" value, if none is passed in the REPL options, and it can be overridden by custom print functions.
stream
A stream is an abstract interface for working with streaming data in Node.js.
The node:stream module provides an API for implementing the stream interface.
Duplex streams are streams that implement both the Readable and Writable interfaces.
The utility function duplexPair returns an Array with two items,
each being a Duplex stream connected to the other side:
Returns the default highWaterMark used by streams.
Defaults to 65536 (64 KiB), or 16 for objectMode.
The stream.PassThrough class is a trivial implementation of a Transform stream that simply passes the input bytes across to the output. Its purpose is
primarily for examples and testing, but there are some use cases where stream.PassThrough is useful as a building block for novel sorts of streams.
A module method to pipe between streams and generators forwarding errors and properly cleaning up and provide a callback when the pipeline is complete.
Transform streams are Duplex streams where the output is in some way
related to the input. Like all Duplex streams, Transform streams
implement both the Readable and Writable interfaces.
Duplex streams are streams that implement both the Readable and Writable interfaces.
The utility function duplexPair returns an Array with two items,
each being a Duplex stream connected to the other side:
Returns the default highWaterMark used by streams.
Defaults to 65536 (64 KiB), or 16 for objectMode.
The stream.PassThrough class is a trivial implementation of a Transform stream that simply passes the input bytes across to the output. Its purpose is
primarily for examples and testing, but there are some use cases where stream.PassThrough is useful as a building block for novel sorts of streams.
A module method to pipe between streams and generators forwarding errors and properly cleaning up and provide a callback when the pipeline is complete.
Transform streams are Duplex streams where the output is in some way
related to the input. Like all Duplex streams, Transform streams
implement both the Readable and Writable interfaces.
- _construct
- _destroy
- _read
- addListener
- asIndexedPairs
- closed
- destroy
- destroyed
- drop
- emit
- errored
- every
- filter
- find
- flatMap
- forEach
- from
- isDisturbed
- isPaused
- iterator
- map
- on
- once
- pause
- prependListener
- prependOnceListener
- push
- read
- readable
- readableAborted
- readableDidRead
- readableEncoding
- readableEnded
- readableFlowing
- readableHighWaterMark
- readableLength
- readableObjectMode
- reduce
- removeListener
- resume
- setEncoding
- some
- take
- toArray
- unpipe
- unshift
- wrap
This Streams API interface provides a built-in byte length queuing strategy that can be used when constructing streams.
This Streams API interface provides a built-in byte length queuing strategy that can be used when constructing streams.
This Streams API interface represents a readable stream of byte data.
This Streams API interface represents a controller allowing control of a WritableStream's state. When constructing a WritableStream, the underlying sink is given a corresponding WritableStreamDefaultController instance to manipulate.
This Streams API interface is the object returned by WritableStream.getWriter() and once created locks the < writer to the WritableStream ensuring that no other streams can write to the underlying sink.
string_decoder
The node:string_decoder module provides an API for decoding Buffer objects
into strings in a manner that preserves encoded multi-byte UTF-8 and UTF-16
characters. It can be accessed using:
The node:string_decoder module provides an API for decoding Buffer objects
into strings in a manner that preserves encoded multi-byte UTF-8 and UTF-16
characters. It can be accessed using:
test/reporters
The node:test/reporters module exposes the builtin-reporters for node:test.
To access it:
The dot reporter outputs the test results in a compact format,
where each passing test is represented by a .,
and each failing test is represented by a X.
timers
The timer module exposes a global API for scheduling functions to
be called at some future period of time. Because the timer functions are
globals, there is no need to import node:timers to use the API.
This object is created internally and is returned from setImmediate(). It
can be passed to clearImmediate() in order to cancel the scheduled
actions.
timers/promises
The timers/promises API provides an alternative set of timer functions
that return Promise objects. The API is accessible via import timersPromises from 'node:timers/promises'.
Returns an async iterator that generates values in an interval of delay ms.
If ref is true, you need to call next() of async iterator explicitly
or implicitly to keep the event loop alive.
tls
The node:tls module provides an implementation of the Transport Layer Security
(TLS) and Secure Socket Layer (SSL) protocols that is built on top of OpenSSL.
The module can be accessed using:
The callback function, if specified, will be added as a listener for the 'secureConnect' event.
[createServer](././tls/~/createServer) sets the default value of the honorCipherOrder option
to true, other APIs that create secure contexts leave it unset.
Creates a new Server. The secureConnectionListener, if provided, is
automatically set as a listener for the 'secureConnection' event.
The default value of the ciphers option of createSecureContext().
It can be assigned any of the supported OpenSSL ciphers.
Defaults to the content of crypto.constants.defaultCoreCipherList, unless
changed using CLI options using --tls-default-ciphers.
The default curve name to use for ECDH key agreement in a tls server.
The default value is 'auto'. See createSecureContext() for further
information.
The default value of the maxVersion option of createSecureContext().
It can be assigned any of the supported TLS protocol versions,
'TLSv1.3', 'TLSv1.2', 'TLSv1.1', or 'TLSv1'. Default: 'TLSv1.3', unless
changed using CLI options. Using --tls-max-v1.2 sets the default to 'TLSv1.2'. Using
--tls-max-v1.3 sets the default to 'TLSv1.3'. If multiple of the options
are provided, the highest maximum is used.
The default value of the minVersion option of createSecureContext().
It can be assigned any of the supported TLS protocol versions,
'TLSv1.3', 'TLSv1.2', 'TLSv1.1', or 'TLSv1'. Default: 'TLSv1.2', unless
changed using CLI options. Using --tls-min-v1.0 sets the default to
'TLSv1'. Using --tls-min-v1.1 sets the default to 'TLSv1.1'. Using
--tls-min-v1.3 sets the default to 'TLSv1.3'. If multiple of the options
are provided, the lowest minimum is used.
Returns an array with the names of the supported TLS ciphers. The names are
lower-case for historical reasons, but must be uppercased to be used in
the ciphers option of [createSecureContext](././tls/~/createSecureContext).
An immutable array of strings representing the root certificates (in PEM format) from the bundled Mozilla CA store as supplied by the current Node.js version.
Accepts encrypted connections using TLS or SSL.
Performs transparent encryption of written data and all required TLS negotiation.
- addListener
- alpnProtocol
- authorizationError
- authorized
- disableRenegotiation
- emit
- enableTrace
- encrypted
- exportKeyingMaterial
- getCertificate
- getCipher
- getEphemeralKeyInfo
- getFinished
- getPeerCertificate
- getPeerFinished
- getPeerX509Certificate
- getProtocol
- getSession
- getSharedSigalgs
- getTLSTicket
- getX509Certificate
- isSessionReused
- on
- once
- prependListener
- prependOnceListener
- renegotiate
- setMaxSendFragment
tty
The node:tty module provides the tty.ReadStream and tty.WriteStream classes. In most cases, it will not be necessary or possible to use this module
directly. However, it can be accessed using:
The tty.isatty() method returns true if the given fd is associated with
a TTY and false if it is not, including whenever fd is not a non-negative
integer.
Represents the readable side of a TTY. In normal circumstances process.stdin will be the only tty.ReadStream instance in a Node.js
process and there should be no reason to create additional instances.
Represents the writable side of a TTY. In normal circumstances, process.stdout and process.stderr will be the onlytty.WriteStream instances created for a Node.js process and there
should be no reason to create additional instances.
url
The node:url module provides utilities for URL resolution and parsing. It can
be accessed using:
Returns the Punycode ASCII serialization of the domain. If domain is an
invalid domain, the empty string is returned.
Returns the Unicode serialization of the domain. If domain is an invalid
domain, the empty string is returned.
This function ensures the correct decodings of percent-encoded characters as well as ensuring a cross-platform valid absolute path string.
This function ensures that path is resolved absolutely, and that the URL
control characters are correctly encoded when converting into a File URL.
The url.resolve() method resolves a target URL relative to a base URL in a
manner similar to that of a web browser resolving an anchor tag.
Browser-compatible URL class, implemented by following the WHATWG URL
Standard. Examples of parsed URLs may be found in the Standard itself.
The URL class is also available on the global object.
The URLSearchParams API provides read and write access to the query of a URL. The URLSearchParams class can also be used standalone with one of the
four following constructors.
The URLSearchParams class is also available on the global object.
This utility function converts a URL object into an ordinary options object as
expected by the http.request() and https.request() APIs.
util
The node:util module supports the needs of Node.js internal APIs. Many of the
utilities are useful for application and module developers as well. To access
it:
Listens to abort event on the provided signal and
returns a promise that is fulfilled when the signal is
aborted. If the passed resource is garbage collected before the signal is
aborted, the returned promise shall remain pending indefinitely.
Takes an async function (or a function that returns a Promise) and returns a
function following the error-first callback style, i.e. taking
an (err, value) => ... callback as the last argument. In the callback, the
first argument will be the rejection reason (or null if the Promise resolved), and the second argument will be the resolved value.
The util.debuglog() method is used to create a function that conditionally
writes debug messages to stderr based on the existence of the NODE_DEBUGenvironment variable. If the section name appears within the value of that
environment variable, then the returned function operates similar to console.error(). If not, then the returned function is a no-op.
The util.deprecate() method wraps fn (which may be a function or class) in
such a way that it is marked as deprecated.
The util.format() method returns a formatted string using the first argument
as a printf-like format string which can contain zero or more format
specifiers. Each specifier is replaced with the converted value from the
corresponding argument. Supported specifiers are:
Returns the string name for a numeric error code that comes from a Node.js API.
The mapping between error codes and error names is platform-dependent.
See Common System Errors for the names of common errors.
Usage of util.inherits() is discouraged. Please use the ES6 class and extends keywords to get language level inheritance support. Also note
that the two styles are semantically incompatible.
The util.inspect() method returns a string representation of object that is
intended for debugging. The output of util.inspect may change at any time
and should not be depended upon programmatically. Additional options may be
passed that alter the result. util.inspect() will use the constructor's name and/or @@toStringTag to make
an identifiable tag for an inspected value.
Returns true if there is deep strict equality between val1 and val2.
Otherwise, returns false.
Provides a higher level API for command-line argument parsing than interacting
with process.argv directly. Takes a specification for the expected arguments
and returns a structured object with the parsed options and positionals.
Takes a function following the common error-first callback style, i.e. taking
an (err, value) => ... callback as the last argument, and returns a version
that returns promises.
An implementation of the WHATWG Encoding Standard TextDecoder API.
An implementation of the WHATWG Encoding Standard TextEncoder API. All
instances of TextEncoder only support UTF-8 encoding.
Returns the string after replacing any surrogate code points
(or equivalently, any unpaired surrogate code units) with the
Unicode "replacement character" U+FFFD.
Returns true if the given object is strictly an Objectand not aFunction (even though functions are objects in JavaScript).
Otherwise, returns false.
Returns true if the value is a built-in ArrayBuffer instance.
This does not include SharedArrayBuffer instances. Usually, it is
desirable to test for both; See util.types.isAnyArrayBuffer() for that.
Returns true if the value is an instance of one of the ArrayBuffer views, such as typed
array objects or DataView. Equivalent to
ArrayBuffer.isView().
Returns true if the value is an async function.
This only reports back what the JavaScript engine is seeing;
in particular, the return value may not match the original source code if
a transpilation tool was used.
Returns true if the value is any boxed primitive object, e.g. created
by new Boolean(), new String() or Object(Symbol()).
Returns true if the value is a generator function.
This only reports back what the JavaScript engine is seeing;
in particular, the return value may not match the original source code if
a transpilation tool was used.
Returns true if the value is a generator object as returned from a
built-in generator function.
This only reports back what the JavaScript engine is seeing;
in particular, the return value may not match the original source code if
a transpilation tool was used.
Returns true if the value is a symbol object, created
by calling Object() on a Symbol primitive.
Returns true if the value is a built-in ArrayBuffer or
SharedArrayBuffer instance.
Returns true if the value is a built-in ArrayBuffer instance.
This does not include SharedArrayBuffer instances. Usually, it is
desirable to test for both; See util.types.isAnyArrayBuffer() for that.
Returns true if the value is an instance of one of the ArrayBuffer views, such as typed
array objects or DataView. Equivalent to
ArrayBuffer.isView().
Returns true if the value is an async function.
This only reports back what the JavaScript engine is seeing;
in particular, the return value may not match the original source code if
a transpilation tool was used.
Returns true if the value is any boxed primitive object, e.g. created
by new Boolean(), new String() or Object(Symbol()).
Returns true if the value is a generator function.
This only reports back what the JavaScript engine is seeing;
in particular, the return value may not match the original source code if
a transpilation tool was used.
Returns true if the value is a generator object as returned from a
built-in generator function.
This only reports back what the JavaScript engine is seeing;
in particular, the return value may not match the original source code if
a transpilation tool was used.
Returns true if the value was returned by the constructor of a built-in Error type.
Returns true if the value is a symbol object, created
by calling Object() on a Symbol primitive.
Called immediately after a promise continuation executes. This may be after a then(), catch(), or finally() handler or before an await after another await.
Called before a promise continuation executes. This can be in the form of then(), catch(), or finally() handlers or an await resuming.
Returns an integer representing a version tag derived from the V8 version,
command-line flags, and detected CPU features. This is useful for determining
whether a vm.Script cachedData buffer is compatible with this instance
of V8.
A subclass of Deserializer corresponding to the format written by DefaultSerializer.
A subclass of Serializer that serializes TypedArray(in particular Buffer) and DataView objects as host objects, and only
stores the part of their underlying ArrayBuffers that they are referring to.
Get statistics about code and its metadata in the heap, see
V8 GetHeapCodeAndMetadataStatistics API. Returns an object with the
following properties:
Generates a snapshot of the current V8 heap and returns a Readable Stream that may be used to read the JSON serialized representation. This JSON stream format is intended to be used with tools such as Chrome DevTools. The JSON schema is undocumented and specific to the V8 engine. Therefore, the schema may change from one version of V8 to the next.
Returns statistics about the V8 heap spaces, i.e. the segments which make up
the V8 heap. Neither the ordering of heap spaces, nor the availability of a
heap space can be guaranteed as the statistics are provided via the
V8 GetHeapSpaceStatistics function and may change from one V8 version to the
next.
Key events in the lifetime of a promise have been categorized into four areas: creation of a promise, before/after a continuation handler is called or around an await, and when the promise resolves or rejects.
Called when a promise is constructed. This does not mean that corresponding before/after events will occur, only that the possibility exists. This will happen if a promise is created without ever getting a continuation.
This is similar to the queryObjects() console API
provided by the Chromium DevTools console. It can be used to search for objects that have the matching constructor on its prototype chain
in the heap after a full garbage collection, which can be useful for memory leak regression tests. To avoid surprising results, users should
avoid using this API on constructors whose implementation they don't control, or on constructors that can be invoked by other parties in the
application.
The v8.setFlagsFromString() method can be used to programmatically set
V8 command-line flags. This method should be used with care. Changing settings
after the VM has started may result in unpredictable behavior, including
crashes and data loss; or it may simply do nothing.
The API is a no-op if --heapsnapshot-near-heap-limit is already set from the command line or the API is called more than once.
limit must be a positive integer. See --heapsnapshot-near-heap-limit for more information.
Called when the promise receives a resolution or rejection value. This may occur synchronously in the case of Promise.resolve() or Promise.reject().
The v8.startupSnapshot interface can be used to add serialization and deserialization hooks for custom startup snapshots.
The v8.stopCoverage() method allows the user to stop the coverage collection
started by NODE_V8_COVERAGE, so that V8 can release the execution count
records and optimize code. This can be used in conjunction with takeCoverage if the user wants to collect the coverage on demand.
The v8.takeCoverage() method allows the user to write the coverage started by NODE_V8_COVERAGE to disk on demand. This method can be invoked multiple
times during the lifetime of the process. Each time the execution counter will
be reset and a new coverage report will be written to the directory specified
by NODE_V8_COVERAGE.
Generates a snapshot of the current V8 heap and writes it to a JSON file. This file is intended to be used with tools such as Chrome DevTools. The JSON schema is undocumented and specific to the V8 engine, and may change from one version of V8 to the next.
vm
The node:vm module enables compiling and running code within V8 Virtual
Machine contexts.
Compiles the given code into the provided context (if no context is
supplied, the current context is used), and returns it wrapped inside a
function with the given params.
This feature is only available with the --experimental-vm-modules command
flag enabled.
The vm.runInContext() method compiles code, runs it within the context of
the contextifiedObject, then returns the result. Running code does not have
access to the local scope. The contextifiedObject object must have been
previously contextified using the createContext method.
The vm.runInNewContext() first contextifies the given contextObject (or
creates a new contextObject if passed as undefined), compiles the code,
runs it within the created context, then returns the result. Running code
does not have access to the local scope.
vm.runInThisContext() compiles code, runs it within the context of the
current global and returns the result. Running code does not have access to
local scope, but does have access to the current global object.
This feature is only available with the --experimental-vm-modules command
flag enabled.
This feature is only available with the --experimental-vm-modules command
flag enabled.
worker_threads
The node:worker_threads module enables the use of threads that execute
JavaScript in parallel. To access it:
Instances of BroadcastChannel allow asynchronous one-to-many communication
with all other BroadcastChannel instances bound to the same channel name.
Within a worker thread, worker.getEnvironmentData() returns a clone
of data passed to the spawning thread's worker.setEnvironmentData().
Every new Worker receives its own copy of the environment data
automatically.
Instances of the worker.MessageChannel class represent an asynchronous,
two-way communications channel.
The MessageChannel has no methods of its own. new MessageChannel() yields an object with port1 and port2 properties, which refer to linked MessagePort instances.
Instances of the worker.MessagePort class represent one end of an
asynchronous, two-way communications channel. It can be used to transfer
structured data, memory regions and other MessagePorts between different Workers.
The worker.setEnvironmentData() API sets the content of worker.getEnvironmentData() in the current thread and all new Worker instances spawned from the current context.
zlib
The node:zlib module provides compression functionality implemented using
Gzip, Deflate/Inflate, and Brotli.
Computes a 32-bit Cyclic Redundancy Check checksum of data.
If value is specified, it is used as the starting value of the checksum, otherwise, 0 is used as the starting value.