Node.js v25.4.0 Documentation

Table of contents

About this documentation
- Contributing
- Stability index
- Stability overview
- JSON output
- System calls and man pages
Usage and example
- Usage
- Example
Assert
- Strict assertion mode
- Legacy assertion mode
- Class: assert.AssertionError
  - new assert.AssertionError(options)
- Class: assert.Assert
  - new assert.Assert([options])
- assert(value[, message])
- assert.deepEqual(actual, expected[, message])
  - Comparison details
- assert.deepStrictEqual(actual, expected[, message])
  - Comparison details
- assert.doesNotMatch(string, regexp[, message])
- assert.doesNotReject(asyncFn[, error][, message])
- assert.doesNotThrow(fn[, error][, message])
- assert.equal(actual, expected[, message])
- assert.fail([message])
- assert.ifError(value)
- assert.match(string, regexp[, message])
- assert.notDeepEqual(actual, expected[, message])
- assert.notDeepStrictEqual(actual, expected[, message])
- assert.notEqual(actual, expected[, message])
- assert.notStrictEqual(actual, expected[, message])
- assert.ok(value[, message])
- assert.rejects(asyncFn[, error][, message])
- assert.strictEqual(actual, expected[, message])
- assert.throws(fn[, error][, message])
- assert.partialDeepStrictEqual(actual, expected[, message])
  - Comparison details
Asynchronous context tracking
- Introduction
- Class: AsyncLocalStorage
- Class: AsyncResource
Async hooks
- Terminology
- Overview
- async_hooks.createHook(callbacks)
  - Error handling
  - Printing in AsyncHook callbacks
- Class: AsyncHook
- Promise execution tracking
- JavaScript embedder API
  - Class: AsyncResource
- Class: AsyncLocalStorage
Buffer
- Buffers and character encodings
- Buffers and TypedArrays
- Buffers and iteration
- Class: Blob
- Class: Buffer
- Class: File
- node:buffer module APIs
- Buffer.from(), Buffer.alloc(), and Buffer.allocUnsafe()
  - The --zero-fill-buffers command-line option
  - What makes Buffer.allocUnsafe() and Buffer.allocUnsafeSlow() "unsafe"?
C++ addons
- Hello world
- Native abstractions for Node.js
- Node-API
- Addon examples
Node-API
- Writing addons in various programming languages
- Implications of ABI stability
  - Enum values in ABI stability
- Building
  - Build tools
    - node-gyp
    - CMake.js
  - Uploading precompiled binaries
- Usage
- Node-API version matrix
- Environment life cycle APIs
  - napi_set_instance_data
  - napi_get_instance_data
- Basic Node-API data types
  - napi_status
  - napi_extended_error_info
  - napi_env
  - node_api_basic_env
  - napi_value
  - napi_threadsafe_function
  - napi_threadsafe_function_release_mode
  - napi_threadsafe_function_call_mode
  - Node-API memory management types
  - Node-API callback types
- Error handling
  - Return values
    - napi_get_last_error_info
  - Exceptions
  - Fatal errors
    - napi_fatal_error
- Object lifetime management
  - Making handle lifespan shorter than that of the native method
  - References to values with a lifespan longer than that of the native method
  - Cleanup on exit of the current Node.js environment
  - Finalization on the exit of the Node.js environment
- Module registration
- Working with JavaScript values
  - Enum types
  - Object creation functions
  - Functions to convert from C types to Node-API
  - Functions to create optimized property keys
  - Functions to convert from Node-API to C types
  - Functions to get global instances
- Working with JavaScript values and abstract operations
  - napi_coerce_to_bool
  - napi_coerce_to_number
  - napi_coerce_to_object
  - napi_coerce_to_string
  - napi_typeof
  - napi_instanceof
  - napi_is_array
  - napi_is_arraybuffer
  - napi_is_buffer
  - napi_is_date
  - napi_is_error
  - napi_is_typedarray
  - napi_is_dataview
  - napi_strict_equals
  - napi_detach_arraybuffer
  - napi_is_detached_arraybuffer
  - node_api_is_sharedarraybuffer
  - node_api_create_sharedarraybuffer
- Working with JavaScript properties
  - Structures
    - napi_property_attributes
    - napi_property_descriptor
  - Functions
- Working with JavaScript functions
  - napi_call_function
  - napi_create_function
  - napi_get_cb_info
  - napi_get_new_target
  - napi_new_instance
- Object wrap
  - napi_define_class
  - napi_wrap
  - napi_unwrap
  - napi_remove_wrap
  - napi_type_tag_object
  - napi_check_object_type_tag
  - napi_add_finalizer
    - node_api_post_finalizer
- Simple asynchronous operations
  - napi_create_async_work
  - napi_delete_async_work
  - napi_queue_async_work
  - napi_cancel_async_work
- Custom asynchronous operations
  - napi_async_init
  - napi_async_destroy
  - napi_make_callback
  - napi_open_callback_scope
  - napi_close_callback_scope
- Version management
  - napi_get_node_version
  - napi_get_version
- Memory management
  - napi_adjust_external_memory
- Promises
  - napi_create_promise
  - napi_resolve_deferred
  - napi_reject_deferred
  - napi_is_promise
- Script execution
  - napi_run_script
- libuv event loop
  - napi_get_uv_event_loop
- Asynchronous thread-safe function calls
  - Calling a thread-safe function
  - Reference counting of thread-safe functions
  - Deciding whether to keep the process running
  - napi_create_threadsafe_function
  - napi_get_threadsafe_function_context
  - napi_call_threadsafe_function
  - napi_acquire_threadsafe_function
  - napi_release_threadsafe_function
  - napi_ref_threadsafe_function
  - napi_unref_threadsafe_function
- Miscellaneous utilities
  - node_api_get_module_file_name
C++ embedder API
- Example embedding application
  - Setting up a per-process state
  - Setting up a per-instance state
Child process
- Asynchronous process creation
- Synchronous process creation
- Class: ChildProcess
- maxBuffer and Unicode
- Shell requirements
- Default Windows shell
- Advanced serialization
Cluster
- How it works
- Class: Worker
  - Event: 'disconnect'
  - Event: 'error'
  - Event: 'exit'
  - Event: 'listening'
  - Event: 'message'
  - Event: 'online'
  - worker.disconnect()
  - worker.exitedAfterDisconnect
  - worker.id
  - worker.isConnected()
  - worker.isDead()
  - worker.kill([signal])
  - worker.process
  - worker.send(message[, sendHandle[, options]][, callback])
- Event: 'disconnect'
- Event: 'exit'
- Event: 'fork'
- Event: 'listening'
- Event: 'message'
- Event: 'online'
- Event: 'setup'
- cluster.disconnect([callback])
- cluster.fork([env])
- cluster.isMaster
- cluster.isPrimary
- cluster.isWorker
- cluster.schedulingPolicy
- cluster.settings
- cluster.setupMaster([settings])
- cluster.setupPrimary([settings])
- cluster.worker
- cluster.workers
Command-line API
- Synopsis
- Program entry point
- Options
- Environment variables
- Useful V8 options
Console
- Class: Console
- Inspector only methods
Crypto
- Determining if crypto support is unavailable
- Asymmetric key types
- Class: Certificate
- Class: Cipheriv
- Class: Decipheriv
- Class: DiffieHellman
- Class: DiffieHellmanGroup
- Class: ECDH
- Class: Hash
- Class: Hmac
  - hmac.digest([encoding])
  - hmac.update(data[, inputEncoding])
- Class: KeyObject
- Class: Sign
  - sign.sign(privateKey[, outputEncoding])
  - sign.update(data[, inputEncoding])
- Class: Verify
  - verify.update(data[, inputEncoding])
  - verify.verify(object, signature[, signatureEncoding])
- Class: X509Certificate
- node:crypto module methods and properties
- Notes
- Crypto constants
Debugger
- Watchers
- Command reference
- Advanced usage
  - V8 inspector integration for Node.js
Deprecated APIs
- Revoking deprecations
- List of deprecated APIs
Diagnostics Channel
- Public API
DNS
- Class: dns.Resolver
  - Resolver([options])
  - resolver.cancel()
  - resolver.setLocalAddress([ipv4][, ipv6])
- dns.getServers()
- dns.lookup(hostname[, options], callback)
  - Supported getaddrinfo flags
- dns.lookupService(address, port, callback)
- dns.resolve(hostname[, rrtype], callback)
- dns.resolve4(hostname[, options], callback)
- dns.resolve6(hostname[, options], callback)
- dns.resolveAny(hostname, callback)
- dns.resolveCname(hostname, callback)
- dns.resolveCaa(hostname, callback)
- dns.resolveMx(hostname, callback)
- dns.resolveNaptr(hostname, callback)
- dns.resolveNs(hostname, callback)
- dns.resolvePtr(hostname, callback)
- dns.resolveSoa(hostname, callback)
- dns.resolveSrv(hostname, callback)
- dns.resolveTlsa(hostname, callback)
- dns.resolveTxt(hostname, callback)
- dns.reverse(ip, callback)
- dns.setDefaultResultOrder(order)
- dns.getDefaultResultOrder()
- dns.setServers(servers)
- DNS promises API
  - Class: dnsPromises.Resolver
  - resolver.cancel()
  - dnsPromises.getServers()
  - dnsPromises.lookup(hostname[, options])
  - dnsPromises.lookupService(address, port)
  - dnsPromises.resolve(hostname[, rrtype])
  - dnsPromises.resolve4(hostname[, options])
  - dnsPromises.resolve6(hostname[, options])
  - dnsPromises.resolveAny(hostname)
  - dnsPromises.resolveCaa(hostname)
  - dnsPromises.resolveCname(hostname)
  - dnsPromises.resolveMx(hostname)
  - dnsPromises.resolveNaptr(hostname)
  - dnsPromises.resolveNs(hostname)
  - dnsPromises.resolvePtr(hostname)
  - dnsPromises.resolveSoa(hostname)
  - dnsPromises.resolveSrv(hostname)
  - dnsPromises.resolveTlsa(hostname)
  - dnsPromises.resolveTxt(hostname)
  - dnsPromises.reverse(ip)
  - dnsPromises.setDefaultResultOrder(order)
  - dnsPromises.getDefaultResultOrder()
  - dnsPromises.setServers(servers)
- Error codes
- Implementation considerations
  - dns.lookup()
  - dns.resolve(), dns.resolve*(), and dns.reverse()
Domain
- Warning: Don't ignore errors!
- Additions to Error objects
- Implicit binding
- Explicit binding
- domain.create()
- Class: Domain
- Domains and promises
Environment Variables
- CLI Environment Variables
- process.env
- DotEnv
Errors
- Error propagation and interception
- Class: Error
- Class: AssertionError
- Class: RangeError
- Class: ReferenceError
- Class: SyntaxError
- Class: SystemError
- Class: TypeError
- Exceptions vs. errors
- OpenSSL errors
- Node.js error codes
- Legacy Node.js error codes
- OpenSSL Error Codes
Events
- Passing arguments and this to listeners
- Asynchronous vs. synchronous
- Handling events only once
- Error events
- Capture rejections of promises
- Class: EventEmitter
- events.defaultMaxListeners
- events.errorMonitor
- events.getEventListeners(emitterOrTarget, eventName)
- events.getMaxListeners(emitterOrTarget)
- events.once(emitter, name[, options])
  - Awaiting multiple events emitted on process.nextTick()
- events.captureRejections
- events.captureRejectionSymbol
- events.listenerCount(emitterOrTarget, eventName)
- events.on(emitter, eventName[, options])
- events.setMaxListeners(n[, ...eventTargets])
- events.addAbortListener(signal, listener)
- Class: events.EventEmitterAsyncResource extends EventEmitter
- EventTarget and Event API
File system
- Promise example
- Callback example
- Synchronous example
- Promises API
- Callback API
- Synchronous API
- Common Objects
- Notes
Global objects
- Class: AbortController
  - abortController.abort([reason])
  - abortController.signal
  - Class: AbortSignal
- Class: Blob
- Class: Buffer
- Class: ByteLengthQueuingStrategy
- __dirname
- __filename
- atob(data)
- Class: BroadcastChannel
- btoa(data)
- clearImmediate(immediateObject)
- clearInterval(intervalObject)
- clearTimeout(timeoutObject)
- Class: CloseEvent
- Class: CompressionStream
- console
- Class: CountQueuingStrategy
- Class: Crypto
- crypto
- Class: CryptoKey
- Class: CustomEvent
- Class: DecompressionStream
- ErrorEvent
- Class: Event
- Class: EventSource
- Class: EventTarget
- exports
- fetch
  - Custom dispatcher
  - Related classes
- Class: File
- Class: FormData
- global
- Class: Headers
- localStorage
- Class: MessageChannel
- Class: MessageEvent
- Class: MessagePort
- module
- Class: Navigator
- navigator
  - navigator.hardwareConcurrency
  - navigator.language
  - navigator.languages
  - navigator.platform
  - navigator.userAgent
  - navigator.locks
- Class: PerformanceEntry
- Class: PerformanceMark
- Class: PerformanceMeasure
- Class: PerformanceObserver
- Class: PerformanceObserverEntryList
- Class: PerformanceResourceTiming
- performance
- process
- queueMicrotask(callback)
- Class: ReadableByteStreamController
- Class: ReadableStream
- Class: ReadableStreamBYOBReader
- Class: ReadableStreamBYOBRequest
- Class: ReadableStreamDefaultController
- Class: ReadableStreamDefaultReader
- require()
- Class: Response
- Class: Request
- sessionStorage
- setImmediate(callback[, ...args])
- setInterval(callback, delay[, ...args])
- setTimeout(callback, delay[, ...args])
- Class: Storage
- structuredClone(value[, options])
- Class: SubtleCrypto
- Class: DOMException
- Class: TextDecoder
- Class: TextDecoderStream
- Class: TextEncoder
- Class: TextEncoderStream
- Class: TransformStream
- Class: TransformStreamDefaultController
- Class: URL
- Class: URLPattern
- Class: URLSearchParams
- Class: WebAssembly
- Class: WebSocket
- Class: WritableStream
- Class: WritableStreamDefaultController
- Class: WritableStreamDefaultWriter
HTTP
- Class: http.Agent
  - new Agent([options])
  - agent.createConnection(options[, callback])
  - agent.keepSocketAlive(socket)
  - agent.reuseSocket(socket, request)
  - agent.destroy()
  - agent.freeSockets
  - agent.getName([options])
  - agent.maxFreeSockets
  - agent.maxSockets
  - agent.maxTotalSockets
  - agent.requests
  - agent.sockets
- Class: http.ClientRequest
  - Event: 'abort'
  - Event: 'close'
  - Event: 'connect'
  - Event: 'continue'
  - Event: 'finish'
  - Event: 'information'
  - Event: 'response'
  - Event: 'socket'
  - Event: 'timeout'
  - Event: 'upgrade'
  - request.abort()
  - request.aborted
  - request.connection
  - request.cork()
  - request.end([data[, encoding]][, callback])
  - request.destroy([error])
    - request.destroyed
  - request.finished
  - request.flushHeaders()
  - request.getHeader(name)
  - request.getHeaderNames()
  - request.getHeaders()
  - request.getRawHeaderNames()
  - request.hasHeader(name)
  - request.maxHeadersCount
  - request.path
  - request.method
  - request.host
  - request.protocol
  - request.removeHeader(name)
  - request.reusedSocket
  - request.setHeader(name, value)
  - request.setNoDelay([noDelay])
  - request.setSocketKeepAlive([enable][, initialDelay])
  - request.setTimeout(timeout[, callback])
  - request.socket
  - request.uncork()
  - request.writableEnded
  - request.writableFinished
  - request.write(chunk[, encoding][, callback])
- Class: http.Server
  - Event: 'checkContinue'
  - Event: 'checkExpectation'
  - Event: 'clientError'
  - Event: 'close'
  - Event: 'connect'
  - Event: 'connection'
  - Event: 'dropRequest'
  - Event: 'request'
  - Event: 'upgrade'
  - server.close([callback])
  - server.closeAllConnections()
  - server.closeIdleConnections()
  - server.headersTimeout
  - server.listen()
  - server.listening
  - server.maxHeadersCount
  - server.requestTimeout
  - server.setTimeout([msecs][, callback])
  - server.maxRequestsPerSocket
  - server.timeout
  - server.keepAliveTimeout
  - server.keepAliveTimeoutBuffer
  - server[Symbol.asyncDispose]()
- Class: http.ServerResponse
  - Event: 'close'
  - Event: 'finish'
  - response.addTrailers(headers)
  - response.connection
  - response.cork()
  - response.end([data[, encoding]][, callback])
  - response.finished
  - response.flushHeaders()
  - response.getHeader(name)
  - response.getHeaderNames()
  - response.getHeaders()
  - response.hasHeader(name)
  - response.headersSent
  - response.removeHeader(name)
  - response.req
  - response.sendDate
  - response.setHeader(name, value)
  - response.setTimeout(msecs[, callback])
  - response.socket
  - response.statusCode
  - response.statusMessage
  - response.strictContentLength
  - response.uncork()
  - response.writableEnded
  - response.writableFinished
  - response.write(chunk[, encoding][, callback])
  - response.writeContinue()
  - response.writeEarlyHints(hints[, callback])
  - response.writeHead(statusCode[, statusMessage][, headers])
  - response.writeProcessing()
- Class: http.IncomingMessage
  - Event: 'aborted'
  - Event: 'close'
  - message.aborted
  - message.complete
  - message.connection
  - message.destroy([error])
  - message.headers
  - message.headersDistinct
  - message.httpVersion
  - message.method
  - message.rawHeaders
  - message.rawTrailers
  - message.setTimeout(msecs[, callback])
  - message.socket
  - message.statusCode
  - message.statusMessage
  - message.trailers
  - message.trailersDistinct
  - message.url
- Class: http.OutgoingMessage
  - Event: 'drain'
  - Event: 'finish'
  - Event: 'prefinish'
  - outgoingMessage.addTrailers(headers)
  - outgoingMessage.appendHeader(name, value)
  - outgoingMessage.connection
  - outgoingMessage.cork()
  - outgoingMessage.destroy([error])
  - outgoingMessage.end(chunk[, encoding][, callback])
  - outgoingMessage.flushHeaders()
  - outgoingMessage.getHeader(name)
  - outgoingMessage.getHeaderNames()
  - outgoingMessage.getHeaders()
  - outgoingMessage.hasHeader(name)
  - outgoingMessage.headersSent
  - outgoingMessage.pipe()
  - outgoingMessage.removeHeader(name)
  - outgoingMessage.setHeader(name, value)
  - outgoingMessage.setHeaders(headers)
  - outgoingMessage.setTimeout(msecs[, callback])
  - outgoingMessage.socket
  - outgoingMessage.uncork()
  - outgoingMessage.writableCorked
  - outgoingMessage.writableEnded
  - outgoingMessage.writableFinished
  - outgoingMessage.writableHighWaterMark
  - outgoingMessage.writableLength
  - outgoingMessage.writableObjectMode
  - outgoingMessage.write(chunk[, encoding][, callback])
- http.METHODS
- http.STATUS_CODES
- http.createServer([options][, requestListener])
- http.get(options[, callback])
- http.get(url[, options][, callback])
- http.globalAgent
- http.maxHeaderSize
- http.request(options[, callback])
- http.request(url[, options][, callback])
- http.validateHeaderName(name[, label])
- http.validateHeaderValue(name, value)
- http.setMaxIdleHTTPParsers(max)
- http.setGlobalProxyFromEnv([proxyEnv])
- Class: WebSocket
- Built-in Proxy Support
  - Proxy URL Format
  - NO_PROXY Format
  - Example
HTTP/2
- Determining if crypto support is unavailable
- Core API
- Compatibility API
- Collecting HTTP/2 performance metrics
- Note on :authority and host
HTTPS
- Determining if crypto support is unavailable
- Class: https.Agent
  - new Agent([options])
    - Event: 'keylog'
- Class: https.Server
- https.createServer([options][, requestListener])
- https.get(options[, callback])
- https.get(url[, options][, callback])
- https.globalAgent
- https.request(options[, callback])
- https.request(url[, options][, callback])
Inspector
- Promises API
  - Class: inspector.Session
- Callback API
  - Class: inspector.Session
- Common Objects
- Integration with DevTools
- Support of breakpoints
Internationalization support
- Options for building Node.js
- Detecting internationalization support
Modules: CommonJS modules
- Enabling
- Accessing the main module
- Package manager tips
- Loading ECMAScript modules using require()
- All together
- Caching
  - Module caching caveats
- Built-in modules
  - Built-in modules with mandatory node: prefix
- Cycles
- File modules
- Folders as modules
- Loading from node_modules folders
- Loading from the global folders
- The module wrapper
- The module scope
- The module object
- The Module object
- Source map v3 support
Modules: ECMAScript modules
- Introduction
- Enabling
- Packages
- import Specifiers
- Import attributes
- Built-in modules
- import() expressions
- import.meta
- Interoperability with CommonJS
- JSON modules
- Wasm modules
- Top-level await
- Loaders
- Resolution and loading algorithm
Modules: node:module API
- The Module object
- Module compile cache
- Customization Hooks
- Source Map Support
Modules: Packages
- Introduction
- Determining module system
- Package entry points
- Dual CommonJS/ES module packages
- Node.js package.json field definitions
Modules: TypeScript
- Enabling
- Full TypeScript support
- Type stripping
Net
- IPC support
  - Identifying paths for IPC connections
- Class: net.BlockList
- Class: net.SocketAddress
- Class: net.Server
- Class: net.Socket
- net.connect()
- net.createConnection()
- net.createServer([options][, connectionListener])
- net.getDefaultAutoSelectFamily()
- net.setDefaultAutoSelectFamily(value)
- net.getDefaultAutoSelectFamilyAttemptTimeout()
- net.setDefaultAutoSelectFamilyAttemptTimeout(value)
- net.isIP(input)
- net.isIPv4(input)
- net.isIPv6(input)
OS
- os.EOL
- os.availableParallelism()
- os.arch()
- os.constants
- os.cpus()
- os.devNull
- os.endianness()
- os.freemem()
- os.getPriority([pid])
- os.homedir()
- os.hostname()
- os.loadavg()
- os.machine()
- os.networkInterfaces()
- os.platform()
- os.release()
- os.setPriority([pid, ]priority)
- os.tmpdir()
- os.totalmem()
- os.type()
- os.uptime()
- os.userInfo([options])
- os.version()
- OS constants
  - Signal constants
  - Error constants
    - POSIX error constants
    - Windows-specific error constants
  - dlopen constants
  - Priority constants
  - libuv constants
Path
- Windows vs. POSIX
- path.basename(path[, suffix])
- path.delimiter
- path.dirname(path)
- path.extname(path)
- path.format(pathObject)
- path.matchesGlob(path, pattern)
- path.isAbsolute(path)
- path.join([...paths])
- path.normalize(path)
- path.parse(path)
- path.posix
- path.relative(from, to)
- path.resolve([...paths])
- path.sep
- path.toNamespacedPath(path)
- path.win32
Performance measurement APIs
- perf_hooks.performance
- Class: PerformanceEntry
- Class: PerformanceMark
  - performanceMark.detail
- Class: PerformanceMeasure
  - performanceMeasure.detail
- Class: PerformanceNodeEntry
- Class: PerformanceNodeTiming
- Class: PerformanceResourceTiming
- Class: PerformanceObserver
- Class: PerformanceObserverEntryList
- perf_hooks.createHistogram([options])
- perf_hooks.eventLoopUtilization([utilization1[, utilization2]])
- perf_hooks.monitorEventLoopDelay([options])
- perf_hooks.timerify(fn[, options])
- Class: Histogram
- Class: IntervalHistogram extends Histogram
- Class: RecordableHistogram extends Histogram
- Examples
Permissions
- Process-based permissions
  - Permission Model
Process
- Process events
  - Event: 'beforeExit'
  - Event: 'disconnect'
  - Event: 'exit'
  - Event: 'message'
  - Event: 'rejectionHandled'
  - Event: 'workerMessage'
  - Event: 'uncaughtException'
    - Warning: Using 'uncaughtException' correctly
  - Event: 'uncaughtExceptionMonitor'
  - Event: 'unhandledRejection'
  - Event: 'warning'
    - Emitting custom warnings
    - Node.js warning names
  - Event: 'worker'
  - Signal events
- process.abort()
- process.allowedNodeEnvironmentFlags
- process.arch
- process.argv
- process.argv0
- process.availableMemory()
- process.channel
  - process.channel.ref()
  - process.channel.unref()
- process.chdir(directory)
- process.config
- process.connected
- process.constrainedMemory()
- process.cpuUsage([previousValue])
- process.cwd()
- process.debugPort
- process.disconnect()
- process.dlopen(module, filename[, flags])
- process.emitWarning(warning[, options])
- process.emitWarning(warning[, type[, code]][, ctor])
  - Avoiding duplicate warnings
- process.env
- process.execArgv
- process.execPath
- process.execve(file[, args[, env]])
- process.exit([code])
- process.exitCode
- process.features.cached_builtins
- process.features.debug
- process.features.inspector
- process.features.ipv6
- process.features.require_module
- process.features.tls
- process.features.tls_alpn
- process.features.tls_ocsp
- process.features.tls_sni
- process.features.typescript
- process.features.uv
- process.finalization.register(ref, callback)
- process.finalization.registerBeforeExit(ref, callback)
- process.finalization.unregister(ref)
- process.getActiveResourcesInfo()
- process.getBuiltinModule(id)
- process.getegid()
- process.geteuid()
- process.getgid()
- process.getgroups()
- process.getuid()
- process.hasUncaughtExceptionCaptureCallback()
- process.hrtime([time])
- process.hrtime.bigint()
- process.initgroups(user, extraGroup)
- process.kill(pid[, signal])
- process.loadEnvFile(path)
- process.mainModule
- process.memoryUsage()
  - A note on process memoryUsage
- process.memoryUsage.rss()
- process.nextTick(callback[, ...args])
  - When to use queueMicrotask() vs. process.nextTick()
- process.noDeprecation
- process.permission
  - process.permission.has(scope[, reference])
- process.pid
- process.platform
- process.ppid
- process.ref(maybeRefable)
- process.release
- process.report
  - process.report.compact
  - process.report.directory
  - process.report.filename
  - process.report.getReport([err])
  - process.report.reportOnFatalError
  - process.report.reportOnSignal
  - process.report.reportOnUncaughtException
  - process.report.excludeEnv
  - process.report.signal
  - process.report.writeReport([filename][, err])
- process.resourceUsage()
- process.send(message[, sendHandle[, options]][, callback])
- process.setegid(id)
- process.seteuid(id)
- process.setgid(id)
- process.setgroups(groups)
- process.setuid(id)
- process.setSourceMapsEnabled(val)
- process.setUncaughtExceptionCaptureCallback(fn)
- process.sourceMapsEnabled
- process.stderr
  - process.stderr.fd
- process.stdin
  - process.stdin.fd
- process.stdout
  - process.stdout.fd
  - A note on process I/O
- process.throwDeprecation
- process.threadCpuUsage([previousValue])
- process.title
- process.traceDeprecation
- process.traceProcessWarnings
- process.umask()
- process.umask(mask)
- process.unref(maybeRefable)
- process.uptime()
- process.version
- process.versions
- Exit codes
Punycode
- punycode.decode(string)
- punycode.encode(string)
- punycode.toASCII(domain)
- punycode.toUnicode(domain)
- punycode.ucs2
  - punycode.ucs2.decode(string)
  - punycode.ucs2.encode(codePoints)
- punycode.version
Query string
- querystring.decode()
- querystring.encode()
- querystring.escape(str)
- querystring.parse(str[, sep[, eq[, options]]])
- querystring.stringify(obj[, sep[, eq[, options]]])
- querystring.unescape(str)
Readline
- Class: InterfaceConstructor
- Promises API
- Callback API
- readline.emitKeypressEvents(stream[, interface])
- Example: Tiny CLI
- Example: Read file stream line-by-Line
- TTY keybindings
REPL
- Design and features
- Class: REPLServer
- repl.builtinModules
- repl.start([options])
- The Node.js REPL
Diagnostic report
- Usage
- Report Version
  - Version history
    - Version 5
    - Version 4
    - Version 3
    - Version 2
    - Version 1
- Configuration
- Interaction with workers
Single executable applications
- Generating single executable preparation blobs
- In the injected main script
- Notes
  - Single executable application creation process
  - Platform support
SQLite
- Class: DatabaseSync
- Class: Session
- Class: StatementSync
- Class: SQLTagStore
- sqlite.backup(sourceDb, path[, options])
- sqlite.constants
  - SQLite constants
    - Conflict resolution constants
    - Authorization constants
      - Authorization result codes
      - Authorization action codes
Stream
- Organization of this document
- Types of streams
- API for stream consumers
- API for stream implementers
- Additional notes
String decoder
- Class: StringDecoder
Test runner
- Subtests
- Skipping tests
- Rerunning failed tests
- TODO tests
- describe() and it() aliases
- only tests
- Filtering tests by name
- Extraneous asynchronous activity
- Watch mode
- Global setup and teardown
- Running tests from the command line
  - Test runner execution model
    - Child process option inheritance
- Collecting code coverage
  - Coverage reporters
- Mocking
  - Timers
  - Dates
- Snapshot testing
- Test reporters
  - Custom reporters
  - Multiple reporters
- run([options])
- suite([name][, options][, fn])
- suite.skip([name][, options][, fn])
- suite.todo([name][, options][, fn])
- suite.only([name][, options][, fn])
- test([name][, options][, fn])
- test.skip([name][, options][, fn])
- test.todo([name][, options][, fn])
- test.only([name][, options][, fn])
- describe([name][, options][, fn])
- describe.skip([name][, options][, fn])
- describe.todo([name][, options][, fn])
- describe.only([name][, options][, fn])
- it([name][, options][, fn])
- it.skip([name][, options][, fn])
- it.todo([name][, options][, fn])
- it.only([name][, options][, fn])
- before([fn][, options])
- after([fn][, options])
- beforeEach([fn][, options])
- afterEach([fn][, options])
- assert
  - assert.register(name, fn)
- snapshot
  - snapshot.setDefaultSnapshotSerializers(serializers)
  - snapshot.setResolveSnapshotPath(fn)
- Class: MockFunctionContext
  - ctx.calls
  - ctx.callCount()
  - ctx.mockImplementation(implementation)
  - ctx.mockImplementationOnce(implementation[, onCall])
  - ctx.resetCalls()
  - ctx.restore()
- Class: MockModuleContext
  - ctx.restore()
- Class: MockPropertyContext
  - ctx.accesses
  - ctx.accessCount()
  - ctx.mockImplementation(value)
  - ctx.mockImplementationOnce(value[, onAccess])
    - Caveat
  - ctx.resetAccesses()
  - ctx.restore()
- Class: MockTracker
  - mock.fn([original[, implementation]][, options])
  - mock.getter(object, methodName[, implementation][, options])
  - mock.method(object, methodName[, implementation][, options])
  - mock.module(specifier[, options])
  - mock.property(object, propertyName[, value])
  - mock.reset()
  - mock.restoreAll()
  - mock.setter(object, methodName[, implementation][, options])
- Class: MockTimers
  - timers.enable([enableOptions])
  - timers.reset()
  - timers[Symbol.dispose]()
  - timers.tick([milliseconds])
    - Using clear functions
    - Working with Node.js timers modules
  - timers.runAll()
  - timers.setTime(milliseconds)
    - Dates and Timers working together
- Class: TestsStream
  - Event: 'test:coverage'
  - Event: 'test:complete'
  - Event: 'test:dequeue'
  - Event: 'test:diagnostic'
  - Event: 'test:enqueue'
  - Event: 'test:fail'
  - Event: 'test:pass'
  - Event: 'test:plan'
  - Event: 'test:start'
  - Event: 'test:stderr'
  - Event: 'test:stdout'
  - Event: 'test:summary'
  - Event: 'test:watch:drained'
  - Event: 'test:watch:restarted'
- Class: TestContext
  - context.before([fn][, options])
  - context.beforeEach([fn][, options])
  - context.after([fn][, options])
  - context.afterEach([fn][, options])
  - context.assert
    - context.assert.fileSnapshot(value, path[, options])
    - context.assert.snapshot(value[, options])
  - context.diagnostic(message)
  - context.filePath
  - context.fullName
  - context.name
  - context.passed
  - context.error
  - context.attempt
  - context.plan(count[,options])
  - context.runOnly(shouldRunOnlyTests)
  - context.signal
  - context.skip([message])
  - context.todo([message])
  - context.test([name][, options][, fn])
  - context.waitFor(condition[, options])
- Class: SuiteContext
  - context.filePath
  - context.fullName
  - context.name
  - context.signal
Timers
- Class: Immediate
- Class: Timeout
- Scheduling timers
- Cancelling timers
- Timers Promises API
TLS (SSL)
- Determining if crypto support is unavailable
- TLS/SSL concepts
  - Perfect forward secrecy
  - ALPN and SNI
  - Pre-shared keys
  - Client-initiated renegotiation attack mitigation
  - Session resumption
    - Session identifiers
    - Session tickets
- Modifying the default TLS cipher suite
- OpenSSL security level
  - Setting security levels
  - Using [--tls-cipher-list][]
- X509 certificate error codes
- Class: tls.Server
  - Event: 'connection'
  - Event: 'keylog'
  - Event: 'newSession'
  - Event: 'OCSPRequest'
  - Event: 'resumeSession'
  - Event: 'secureConnection'
  - Event: 'tlsClientError'
  - server.addContext(hostname, context)
  - server.address()
  - server.close([callback])
  - server.getTicketKeys()
  - server.listen()
  - server.setSecureContext(options)
  - server.setTicketKeys(keys)
- Class: tls.TLSSocket
  - new tls.TLSSocket(socket[, options])
  - Event: 'keylog'
  - Event: 'OCSPResponse'
  - Event: 'secureConnect'
  - Event: 'session'
  - tlsSocket.address()
  - tlsSocket.authorizationError
  - tlsSocket.authorized
  - tlsSocket.disableRenegotiation()
  - tlsSocket.enableTrace()
  - tlsSocket.encrypted
  - tlsSocket.exportKeyingMaterial(length, label[, context])
  - tlsSocket.getCertificate()
  - tlsSocket.getCipher()
  - tlsSocket.getEphemeralKeyInfo()
  - tlsSocket.getFinished()
  - tlsSocket.getPeerCertificate([detailed])
    - Certificate object
  - tlsSocket.getPeerFinished()
  - tlsSocket.getPeerX509Certificate()
  - tlsSocket.getProtocol()
  - tlsSocket.getSession()
  - tlsSocket.getSharedSigalgs()
  - tlsSocket.getTLSTicket()
  - tlsSocket.getX509Certificate()
  - tlsSocket.isSessionReused()
  - tlsSocket.localAddress
  - tlsSocket.localPort
  - tlsSocket.remoteAddress
  - tlsSocket.remoteFamily
  - tlsSocket.remotePort
  - tlsSocket.renegotiate(options, callback)
  - tlsSocket.setKeyCert(context)
  - tlsSocket.setMaxSendFragment(size)
- tls.checkServerIdentity(hostname, cert)
- tls.connect(options[, callback])
- tls.connect(path[, options][, callback])
- tls.connect(port[, host][, options][, callback])
- tls.createSecureContext([options])
- tls.createServer([options][, secureConnectionListener])
- tls.setDefaultCACertificates(certs)
- tls.getCACertificates([type])
- tls.getCiphers()
- tls.rootCertificates
- tls.DEFAULT_ECDH_CURVE
- tls.DEFAULT_MAX_VERSION
- tls.DEFAULT_MIN_VERSION
- tls.DEFAULT_CIPHERS
Trace events
- The node:trace_events module
- Examples
  - Collect trace events data by inspector
TTY
- Class: tty.ReadStream
- Class: tty.WriteStream
- tty.isatty(fd)
UDP/datagram sockets
- Class: dgram.Socket
- node:dgram module functions
  - dgram.createSocket(options[, callback])
  - dgram.createSocket(type[, callback])
URL
- URL strings and URL objects
  - Constructing a URL from component parts and getting the constructed string
- The WHATWG URL API
- Legacy URL API
- Percent-encoding in URLs
  - Legacy API
  - WHATWG API
Util
- util.callbackify(original)
- util.convertProcessSignalToExitCode(signalCode)
- util.debuglog(section[, callback])
  - debuglog().enabled
- util.debug(section)
- util.deprecate(fn, msg[, code[, options]])
- util.diff(actual, expected)
- util.format(format[, ...args])
- util.formatWithOptions(inspectOptions, format[, ...args])
- util.getCallSites([frameCount][, options])
- util.getSystemErrorName(err)
- util.getSystemErrorMap()
- util.getSystemErrorMessage(err)
- util.setTraceSigInt(enable)
- util.inherits(constructor, superConstructor)
- util.inspect(object[, options])
- util.inspect(object[, showHidden[, depth[, colors]]])
  - Customizing util.inspect colors
  - Custom inspection functions on objects
  - util.inspect.custom
  - util.inspect.defaultOptions
- util.isDeepStrictEqual(val1, val2[, options])
- Class: util.MIMEType
  - new MIMEType(input)
  - mime.type
  - mime.subtype
  - mime.essence
  - mime.params
  - mime.toString()
  - mime.toJSON()
- Class: util.MIMEParams
  - new MIMEParams()
  - mimeParams.delete(name)
  - mimeParams.entries()
  - mimeParams.get(name)
  - mimeParams.has(name)
  - mimeParams.keys()
  - mimeParams.set(name, value)
  - mimeParams.values()
  - mimeParams[Symbol.iterator]()
- util.parseArgs([config])
  - parseArgs tokens
- util.parseEnv(content)
- util.promisify(original)
  - Custom promisified functions
  - util.promisify.custom
- util.stripVTControlCharacters(str)
- util.styleText(format, text[, options])
- Class: util.TextDecoder
  - WHATWG supported encodings
  - new TextDecoder([encoding[, options]])
  - textDecoder.decode([input[, options]])
  - textDecoder.encoding
  - textDecoder.fatal
  - textDecoder.ignoreBOM
- Class: util.TextEncoder
  - textEncoder.encode([input])
  - textEncoder.encodeInto(src, dest)
  - textEncoder.encoding
- util.toUSVString(string)
- util.transferableAbortController()
- util.transferableAbortSignal(signal)
- util.aborted(signal, resource)
- util.types
  - util.types.isAnyArrayBuffer(value)
  - util.types.isArrayBufferView(value)
  - util.types.isArgumentsObject(value)
  - util.types.isArrayBuffer(value)
  - util.types.isAsyncFunction(value)
  - util.types.isBigInt64Array(value)
  - util.types.isBigIntObject(value)
  - util.types.isBigUint64Array(value)
  - util.types.isBooleanObject(value)
  - util.types.isBoxedPrimitive(value)
  - util.types.isCryptoKey(value)
  - util.types.isDataView(value)
  - util.types.isDate(value)
  - util.types.isExternal(value)
  - util.types.isFloat16Array(value)
  - util.types.isFloat32Array(value)
  - util.types.isFloat64Array(value)
  - util.types.isGeneratorFunction(value)
  - util.types.isGeneratorObject(value)
  - util.types.isInt8Array(value)
  - util.types.isInt16Array(value)
  - util.types.isInt32Array(value)
  - util.types.isKeyObject(value)
  - util.types.isMap(value)
  - util.types.isMapIterator(value)
  - util.types.isModuleNamespaceObject(value)
  - util.types.isNativeError(value)
  - util.types.isNumberObject(value)
  - util.types.isPromise(value)
  - util.types.isProxy(value)
  - util.types.isRegExp(value)
  - util.types.isSet(value)
  - util.types.isSetIterator(value)
  - util.types.isSharedArrayBuffer(value)
  - util.types.isStringObject(value)
  - util.types.isSymbolObject(value)
  - util.types.isTypedArray(value)
  - util.types.isUint8Array(value)
  - util.types.isUint8ClampedArray(value)
  - util.types.isUint16Array(value)
  - util.types.isUint32Array(value)
  - util.types.isWeakMap(value)
  - util.types.isWeakSet(value)
- Deprecated APIs
  - util._extend(target, source)
  - util.isArray(object)
V8
- v8.cachedDataVersionTag()
- v8.getHeapCodeStatistics()
- v8.getHeapSnapshot([options])
- v8.getHeapSpaceStatistics()
- v8.getHeapStatistics()
- v8.getCppHeapStatistics([detailLevel])
- v8.queryObjects(ctor[, options])
- v8.setFlagsFromString(flags)
- v8.stopCoverage()
- v8.takeCoverage()
- v8.writeHeapSnapshot([filename[,options]])
- v8.setHeapSnapshotNearHeapLimit(limit)
- Serialization API
  - v8.serialize(value)
  - v8.deserialize(buffer)
  - Class: v8.Serializer
  - Class: v8.Deserializer
  - Class: v8.DefaultSerializer
  - Class: v8.DefaultDeserializer
- Promise hooks
  - promiseHooks.onInit(init)
  - promiseHooks.onSettled(settled)
  - promiseHooks.onBefore(before)
  - promiseHooks.onAfter(after)
  - promiseHooks.createHook(callbacks)
  - Hook callbacks
- Startup Snapshot API
  - v8.startupSnapshot.addSerializeCallback(callback[, data])
  - v8.startupSnapshot.addDeserializeCallback(callback[, data])
  - v8.startupSnapshot.setDeserializeMainFunction(callback[, data])
  - v8.startupSnapshot.isBuildingSnapshot()
- Class: v8.GCProfiler
  - new v8.GCProfiler()
  - profiler.start()
  - profiler.stop()
- Class: SyncCPUProfileHandle
  - syncCpuProfileHandle.stop()
  - syncCpuProfileHandle[Symbol.dispose]()
- Class: CPUProfileHandle
  - cpuProfileHandle.stop()
  - cpuProfileHandle[Symbol.asyncDispose]()
- Class: HeapProfileHandle
  - heapProfileHandle.stop()
  - heapProfileHandle[Symbol.asyncDispose]()
- v8.isStringOneByteRepresentation(content)
- v8.startCpuProfile()
VM (executing JavaScript)
- Class: vm.Script
- Class: vm.Module
- Class: vm.SourceTextModule
- Class: vm.SyntheticModule
  - new vm.SyntheticModule(exportNames, evaluateCallback[, options])
  - syntheticModule.setExport(name, value)
- Type: ModuleRequest
- vm.compileFunction(code[, params[, options]])
- vm.constants
  - vm.constants.USE_MAIN_CONTEXT_DEFAULT_LOADER
- vm.createContext([contextObject[, options]])
- vm.isContext(object)
- vm.measureMemory([options])
- vm.runInContext(code, contextifiedObject[, options])
- vm.runInNewContext(code[, contextObject[, options]])
- vm.runInThisContext(code[, options])
- Example: Running an HTTP server within a VM
- What does it mean to "contextify" an object?
  - vm.constants.DONT_CONTEXTIFY
- Timeout interactions with asynchronous tasks and Promises
  - When microtaskMode is 'afterEvaluate', beware sharing Promises between Contexts
- Support of dynamic import() in compilation APIs
WebAssembly System Interface (WASI)
- Security
- Class: WASI
Web Crypto API
- Modern Algorithms in the Web Cryptography API
- Secure Curves in the Web Cryptography API
- Examples
- Algorithm matrix
  - Key Management APIs
  - Crypto Operation APIs
- Class: Crypto
- Class: CryptoKey
- Class: CryptoKeyPair
  - cryptoKeyPair.privateKey
  - cryptoKeyPair.publicKey
- Class: SubtleCrypto
- Algorithm parameters
Web Streams API
- Overview
  - Example ReadableStream
  - Node.js streams interoperability
- API
Worker threads
- worker_threads.getEnvironmentData(key)
- worker_threads.isInternalThread
- worker_threads.isMainThread
- worker_threads.markAsUntransferable(object)
- worker_threads.isMarkedAsUntransferable(object)
- worker_threads.markAsUncloneable(object)
- worker_threads.moveMessagePortToContext(port, contextifiedSandbox)
- worker_threads.parentPort
- worker_threads.postMessageToThread(threadId, value[, transferList][, timeout])
- worker_threads.receiveMessageOnPort(port)
- worker_threads.resourceLimits
- worker_threads.SHARE_ENV
- worker_threads.setEnvironmentData(key[, value])
- worker_threads.threadId
- worker_threads.threadName
- worker_threads.workerData
- worker_threads.locks
  - Class: Lock
    - lock.name
    - lock.mode
  - Class: LockManager
    - locks.request(name[, options], callback)
    - locks.query()
- Class: BroadcastChannel extends EventTarget
  - new BroadcastChannel(name)
  - broadcastChannel.close()
  - broadcastChannel.onmessage
  - broadcastChannel.onmessageerror
  - broadcastChannel.postMessage(message)
  - broadcastChannel.ref()
  - broadcastChannel.unref()
- Class: MessageChannel
- Class: MessagePort
  - Event: 'close'
  - Event: 'message'
  - Event: 'messageerror'
  - port.close()
  - port.postMessage(value[, transferList])
    - Considerations when transferring TypedArrays and Buffers
    - Considerations when cloning objects with prototypes, classes, and accessors
  - port.hasRef()
  - port.ref()
  - port.start()
  - port.unref()
- Class: Worker
  - new Worker(filename[, options])
  - Event: 'error'
  - Event: 'exit'
  - Event: 'message'
  - Event: 'messageerror'
  - Event: 'online'
  - worker.cpuUsage([prev])
  - worker.getHeapSnapshot([options])
  - worker.getHeapStatistics()
  - worker.performance
    - performance.eventLoopUtilization([utilization1[, utilization2]])
  - worker.postMessage(value[, transferList])
  - worker.ref()
  - worker.resourceLimits
  - worker.startCpuProfile()
  - worker.startHeapProfile()
  - worker.stderr
  - worker.stdin
  - worker.stdout
  - worker.terminate()
  - worker.threadId
  - worker.threadName
  - worker.unref()
  - worker[Symbol.asyncDispose]()
- Notes
  - Synchronous blocking of stdio
  - Launching worker threads from preload scripts
Zlib
- Threadpool usage and performance considerations
- Compressing HTTP requests and responses
- Memory usage tuning
  - For zlib-based streams
  - For Brotli-based streams
  - For Zstd-based streams
- Flushing
- Constants
  - zlib constants
  - Brotli constants
  - Zstd constants
- Class: Options
- Class: BrotliOptions
- Class: zlib.BrotliCompress
- Class: zlib.BrotliDecompress
- Class: zlib.Deflate
- Class: zlib.DeflateRaw
- Class: zlib.Gunzip
- Class: zlib.Gzip
- Class: zlib.Inflate
- Class: zlib.InflateRaw
- Class: zlib.Unzip
- Class: zlib.ZlibBase
  - zlib.bytesWritten
  - zlib.close([callback])
  - zlib.flush([kind, ]callback)
  - zlib.params(level, strategy, callback)
  - zlib.reset()
- Class: ZstdOptions
- Class: zlib.ZstdCompress
- Class: zlib.ZstdDecompress
- zlib.constants
- zlib.crc32(data[, value])
- zlib.createBrotliCompress([options])
- zlib.createBrotliDecompress([options])
- zlib.createDeflate([options])
- zlib.createDeflateRaw([options])
- zlib.createGunzip([options])
- zlib.createGzip([options])
- zlib.createInflate([options])
- zlib.createInflateRaw([options])
- zlib.createUnzip([options])
- zlib.createZstdCompress([options])
- zlib.createZstdDecompress([options])
- Convenience methods
  - zlib.brotliCompress(buffer[, options], callback)
  - zlib.brotliCompressSync(buffer[, options])
  - zlib.brotliDecompress(buffer[, options], callback)
  - zlib.brotliDecompressSync(buffer[, options])
  - zlib.deflate(buffer[, options], callback)
  - zlib.deflateSync(buffer[, options])
  - zlib.deflateRaw(buffer[, options], callback)
  - zlib.deflateRawSync(buffer[, options])
  - zlib.gunzip(buffer[, options], callback)
  - zlib.gunzipSync(buffer[, options])
  - zlib.gzip(buffer[, options], callback)
  - zlib.gzipSync(buffer[, options])
  - zlib.inflate(buffer[, options], callback)
  - zlib.inflateSync(buffer[, options])
  - zlib.inflateRaw(buffer[, options], callback)
  - zlib.inflateRawSync(buffer[, options])
  - zlib.unzip(buffer[, options], callback)
  - zlib.unzipSync(buffer[, options])
  - zlib.zstdCompress(buffer[, options], callback)
  - zlib.zstdCompressSync(buffer[, options])
  - zlib.zstdDecompress(buffer[, options], callback)
  - zlib.zstdDecompressSync(buffer[, options])

About this documentation#

Welcome to the official API reference documentation for Node.js!

Node.js is a JavaScript runtime built on the V8 JavaScript engine.

Contributing#

Report errors in this documentation in the issue tracker. See the contributing guide for directions on how to submit pull requests.

Stability index#

Throughout the documentation are indications of a section's stability. Some APIs are so proven and so relied upon that they are unlikely to ever change at all. Others are brand new and experimental, or known to be hazardous.

The stability indexes are as follows:

Stability: 0 - Deprecated. The feature may emit warnings. Backward compatibility is not guaranteed.

Stability: 1 - Experimental. The feature is not subject to semantic versioning rules. Non-backward compatible changes or removal may occur in any future release. Use of the feature is not recommended in production environments.

Experimental features are subdivided into stages:

1.0 - Early development. Experimental features at this stage are unfinished and subject to substantial change.
1.1 - Active development. Experimental features at this stage are nearing minimum viability.
1.2 - Release candidate. Experimental features at this stage are hopefully ready to become stable. No further breaking changes are anticipated but may still occur in response to user feedback or the features' underlying specification development. We encourage user testing and feedback so that we can know that this feature is ready to be marked as stable.

Experimental features leave the experimental status typically either by graduating to stable, or are removed without a deprecation cycle.

Stability: 2 - Stable. Compatibility with the npm