Node.js v9.9.0 Documentation

Table of Contents

Deprecated APIs#

Node.js may deprecate APIs when either: (a) use of the API is considered to be unsafe, (b) an improved alternative API has been made available, or (c) breaking changes to the API are expected in a future major release.

Node.js utilizes three kinds of Deprecations:

  • Documentation-only
  • Runtime
  • End-of-Life

A Documentation-only deprecation is one that is expressed only within the Node.js API docs. These generate no side-effects while running Node.js. Some Documentation-only deprecations trigger a runtime warning when launched with [--pending-deprecation][] flag (or its alternative, NODE_PENDING_DEPRECATION=1 environment variable), similarly to Runtime deprecations below. Documentation-only deprecations that support that flag are explicitly labeled as such in the list of Deprecated APIs.

A Runtime deprecation will, by default, generate a process warning that will be printed to stderr the first time the deprecated API is used. When the --throw-deprecation command-line flag is used, a Runtime deprecation will cause an error to be thrown.

An End-of-Life deprecation is used to identify code that either has been removed or will soon be removed from Node.js.

Un-deprecation#

From time-to-time the deprecation of an API may be reversed. Such action may happen in either a semver-minor or semver-major release. In such situations, this document will be updated with information relevant to the decision. However, the deprecation identifier will not be modified.

List of Deprecated APIs#

DEP0001: http.OutgoingMessage.prototype.flush#

Type: Runtime

The OutgoingMessage.prototype.flush() method is deprecated. Use OutgoingMessage.prototype.flushHeaders() instead.

DEP0002: require('_linklist')#

Type: End-of-Life

The _linklist module is deprecated. Please use a userland alternative.

DEP0003: _writableState.buffer#

Type: Runtime

The _writableState.buffer property is deprecated. Use the _writableState.getBuffer() method instead.

DEP0004: CryptoStream.prototype.readyState#

Type: Documentation-only

The CryptoStream.prototype.readyState property is deprecated and should not be used.

DEP0005: Buffer() constructor#

Type: Documentation-only (supports [--pending-deprecation][])

The Buffer() function and new Buffer() constructor are deprecated due to API usability issues that can potentially lead to accidental security issues.

As an alternative, use of the following methods of constructing Buffer objects is strongly recommended:

DEP0006: child_process options.customFds#

Type: Runtime

Within the child_process module's spawn(), fork(), and exec() methods, the options.customFds option is deprecated. The options.stdio option should be used instead.

DEP0007: Replace cluster worker.suicide with worker.exitedAfterDisconnect#

Type: End-of-Life

In an earlier version of the Node.js cluster, a boolean property with the name suicide was added to the Worker object. The intent of this property was to provide an indication of how and why the Worker instance exited. In Node.js 6.0.0, the old property was deprecated and replaced with a new worker.exitedAfterDisconnect property. The old property name did not precisely describe the actual semantics and was unnecessarily emotion-laden.

DEP0008: require('constants')#

Type: Documentation-only

The constants module has been deprecated. When requiring access to constants relevant to specific Node.js builtin modules, developers should instead refer to the constants property exposed by the relevant module. For instance, require('fs').constants and require('os').constants.

DEP0009: crypto.pbkdf2 without digest#

Type: End-of-life

Use of the crypto.pbkdf2() API without specifying a digest was deprecated in Node.js 6.0 because the method defaulted to using the non-recommended 'SHA1' digest. Previously, a deprecation warning was printed. Starting in Node.js 8.0.0, calling crypto.pbkdf2() or crypto.pbkdf2Sync() with an undefined digest will throw a TypeError.

DEP0010: crypto.createCredentials#

Type: Runtime

The crypto.createCredentials() API is deprecated. Please use tls.createSecureContext() instead.

DEP0011: crypto.Credentials#

Type: Runtime

The crypto.Credentials class is deprecated. Please use tls.SecureContext instead.

DEP0012: Domain.dispose#

Type: End-of-Life

Domain.dispose() is removed. Recover from failed I/O actions explicitly via error event handlers set on the domain instead.

DEP0013: fs asynchronous function without callback#

Type: Runtime

Calling an asynchronous function without a callback is deprecated.

DEP0014: fs.read legacy String interface#

Type: End-of-Life

The fs.read() legacy String interface is deprecated. Use the Buffer API as mentioned in the documentation instead.

DEP0015: fs.readSync legacy String interface#

Type: End-of-Life

The fs.readSync() legacy String interface is deprecated. Use the Buffer API as mentioned in the documentation instead.

DEP0016: GLOBAL/root#

Type: Runtime

The GLOBAL and root aliases for the global property have been deprecated and should no longer be used.

DEP0017: Intl.v8BreakIterator#

Type: End-of-Life

Intl.v8BreakIterator was a non-standard extension and has been removed. See Intl.Segmenter.

DEP0018: Unhandled promise rejections#

Type: Runtime

Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

DEP0019: require('.') resolved outside directory#

Type: Runtime

In certain cases, require('.') may resolve outside the package directory. This behavior is deprecated and will be removed in a future major Node.js release.

DEP0020: Server.connections#

Type: Runtime

The Server.connections property is deprecated. Please use the Server.getConnections() method instead.

DEP0021: Server.listenFD#

Type: Runtime

The Server.listenFD() method is deprecated. Please use Server.listen({fd: <number>}) instead.

DEP0022: os.tmpDir()#

Type: Runtime

The os.tmpDir() API is deprecated. Please use os.tmpdir() instead.

DEP0023: os.getNetworkInterfaces()#

Type: Runtime

The os.getNetworkInterfaces() method is deprecated. Please use the os.networkInterfaces property instead.

DEP0024: REPLServer.prototype.convertToContext()#

Type: End-of-Life

The REPLServer.prototype.convertToContext() API is deprecated and should not be used.

DEP0025: require('sys')#

Type: Runtime

The sys module is deprecated. Please use the util module instead.

DEP0026: util.print()#

Type: Runtime

The util.print() API is deprecated. Please use console.log() instead.

DEP0027: util.puts()#

Type: Runtime

The util.puts() API is deprecated. Please use console.log() instead.

DEP0028: util.debug()#

Type: Runtime

The util.debug() API is deprecated. Please use console.error() instead.

DEP0029: util.error()#

Type: Runtime

The util.error() API is deprecated. Please use console.error() instead.

DEP0030: SlowBuffer#

Type: Documentation-only

The SlowBuffer class has been deprecated. Please use Buffer.allocUnsafeSlow(size) instead.

DEP0031: ecdh.setPublicKey()#

Type: Documentation-only

The ecdh.setPublicKey() method is now deprecated as its inclusion in the API is not useful.

DEP0032: domain module#

Type: Documentation-only

The domain module is deprecated and should not be used.

DEP0033: EventEmitter.listenerCount()#

Type: Documentation-only

The EventEmitter.listenerCount(emitter, eventName) API has been deprecated. Please use emitter.listenerCount(eventName) instead.

DEP0034: fs.exists(path, callback)#

Type: Documentation-only

The fs.exists(path, callback) API has been deprecated. Please use fs.stat() or fs.access() instead.

DEP0035: fs.lchmod(path, mode, callback)#

Type: Documentation-only

The fs.lchmod(path, mode, callback) API has been deprecated.

DEP0036: fs.lchmodSync(path, mode)#

Type: Documentation-only

The fs.lchmodSync(path, mode) API has been deprecated.

DEP0037: fs.lchown(path, uid, gid, callback)#

Type: Documentation-only

The fs.lchown(path, uid, gid, callback) API has been deprecated.

DEP0038: fs.lchownSync(path, uid, gid)#

Type: Documentation-only

The fs.lchownSync(path, uid, gid) API has been deprecated.

DEP0039: require.extensions#

Type: Documentation-only

The require.extensions property has been deprecated.

DEP0040: punycode module#

Type: Documentation-only

The punycode module has been deprecated. Please use a userland alternative instead.

DEP0041: NODE_REPL_HISTORY_FILE environment variable#

Type: Documentation-only

The NODE_REPL_HISTORY_FILE environment variable has been deprecated.

DEP0042: tls.CryptoStream#

Type: Documentation-only

The tls.CryptoStream class has been deprecated. Please use tls.TLSSocket instead.

DEP0043: tls.SecurePair#

Type: Documentation-only

The tls.SecurePair class has been deprecated. Please use tls.TLSSocket instead.

DEP0044: util.isArray()#

Type: Documentation-only

The util.isArray() API has been deprecated. Please use Array.isArray() instead.

DEP0045: util.isBoolean()#

Type: Documentation-only

The util.isBoolean() API has been deprecated.

DEP0046: util.isBuffer()#

Type: Documentation-only

The util.isBuffer() API has been deprecated. Please use Buffer.isBuffer() instead.

DEP0047: util.isDate()#

Type: Documentation-only

The util.isDate() API has been deprecated.

DEP0048: util.isError()#

Type: Documentation-only

The util.isError() API has been deprecated.

DEP0049: util.isFunction()#

Type: Documentation-only

The util.isFunction() API has been deprecated.

DEP0050: util.isNull()#

Type: Documentation-only

The util.isNull() API has been deprecated.

DEP0051: util.isNullOrUndefined()#

Type: Documentation-only

The util.isNullOrUndefined() API has been deprecated.

DEP0052: util.isNumber()#

Type: Documentation-only

The util.isNumber() API has been deprecated.

DEP0053 util.isObject()#

Type: Documentation-only

The util.isObject() API has been deprecated.

DEP0054: util.isPrimitive()#

Type: Documentation-only

The util.isPrimitive() API has been deprecated.

DEP0055: util.isRegExp()#

Type: Documentation-only

The util.isRegExp() API has been deprecated.

DEP0056: util.isString()#

Type: Documentation-only

The util.isString() API has been deprecated.

DEP0057: util.isSymbol()#

Type: Documentation-only

The util.isSymbol() API has been deprecated.

DEP0058: util.isUndefined()#

Type: Documentation-only

The util.isUndefined() API has been deprecated.

DEP0059: util.log()#

Type: Documentation-only

The util.log() API has been deprecated.

DEP0060: util._extend()#

Type: Documentation-only

The util._extend() API has been deprecated.

DEP0061: fs.SyncWriteStream#

Type: Runtime

The fs.SyncWriteStream class was never intended to be a publicly accessible API. No alternative API is available. Please use a userland alternative.

DEP0062: node --debug#

Type: Runtime

--debug activates the legacy V8 debugger interface, which has been removed as of V8 5.8. It is replaced by Inspector which is activated with --inspect instead.

DEP0063: ServerResponse.prototype.writeHeader()#

Type: Documentation-only

The http module ServerResponse.prototype.writeHeader() API has been deprecated. Please use ServerResponse.prototype.writeHead() instead.

Note: The ServerResponse.prototype.writeHeader() method was never documented as an officially supported API.

DEP0064: tls.createSecurePair()#

Type: Runtime

The tls.createSecurePair() API was deprecated in documentation in Node.js 0.11.3. Users should use tls.Socket instead.

DEP0065: repl.REPL_MODE_MAGIC and NODE_REPL_MODE=magic#

Type: Documentation-only

The repl module's REPL_MODE_MAGIC constant, used for replMode option, has been deprecated. Its behavior has been functionally identical to that of REPL_MODE_SLOPPY since Node.js v6.0.0, when V8 5.0 was imported. Please use REPL_MODE_SLOPPY instead.

The NODE_REPL_MODE environment variable is used to set the underlying replMode of an interactive node session. Its default value, magic, is similarly deprecated in favor of sloppy.

DEP0066: outgoingMessage._headers, outgoingMessage._headerNames#

Type: Documentation-only

The http module outgoingMessage._headers and outgoingMessage._headerNames properties have been deprecated. Please instead use one of the public methods (e.g. outgoingMessage.getHeader(), outgoingMessage.getHeaders(), outgoingMessage.getHeaderNames(), outgoingMessage.hasHeader(), outgoingMessage.removeHeader(), outgoingMessage.setHeader()) for working with outgoing headers.

Note: outgoingMessage._headers and outgoingMessage._headerNames were never documented as officially supported properties.

DEP0067: OutgoingMessage.prototype._renderHeaders#

Type: Documentation-only

The http module OutgoingMessage.prototype._renderHeaders() API has been deprecated.

Note: OutgoingMessage.prototype._renderHeaders was never documented as an officially supported API.

DEP0068: node debug#

Type: Runtime

node debug corresponds to the legacy CLI debugger which has been replaced with a V8-inspector based CLI debugger available through node inspect.

DEP0069: vm.runInDebugContext(string)#

Type: Runtime

The DebugContext will be removed in V8 soon and will not be available in Node 10+.

Note: DebugContext was an experimental API.

DEP0070: async_hooks.currentId()#

Type: End-of-Life

async_hooks.currentId() was renamed to async_hooks.executionAsyncId() for clarity.

Note: change was made while async_hooks was an experimental API.

DEP0071: async_hooks.triggerId()#

Type: End-of-Life

async_hooks.triggerId() was renamed to async_hooks.triggerAsyncId() for clarity.

Note: change was made while async_hooks was an experimental API.

DEP0072: async_hooks.AsyncResource.triggerId()#

Type: End-of-Life

async_hooks.AsyncResource.triggerId() was renamed to async_hooks.AsyncResource.triggerAsyncId() for clarity.

Note: change was made while async_hooks was an experimental API.

DEP0073: Several internal properties of net.Server#

Type: Runtime

Accessing several internal, undocumented properties of net.Server instances with inappropriate names has been deprecated.

Note: As the original API was undocumented and not generally useful for non-internal code, no replacement API is provided.

DEP0074: REPLServer.bufferedCommand#

Type: Runtime

The REPLServer.bufferedCommand property was deprecated in favor of REPLServer.clearBufferedCommand().

DEP0075: REPLServer.parseREPLKeyword()#

Type: Runtime

REPLServer.parseREPLKeyword() was removed from userland visibility.

DEP0076: tls.parseCertString()#

Type: Runtime

tls.parseCertString() is a trivial parsing helper that was made public by mistake. This function can usually be replaced with:

const querystring = require('querystring');
querystring.parse(str, '\n', '=');

Note: This function is not completely equivalent to querystring.parse(). One difference is that querystring.parse() does url decoding:

> querystring.parse('%E5%A5%BD=1', '\n', '=');
{ '好': '1' }
> tls.parseCertString('%E5%A5%BD=1');
{ '%E5%A5%BD': '1' }

DEP0077: Module._debug()#

Type: Runtime

Module._debug() has been deprecated.

Note: Module._debug() was never documented as an officially supported API.

DEP0078: REPLServer.turnOffEditorMode()#

Type: Runtime

REPLServer.turnOffEditorMode() was removed from userland visibility.

DEP0079: Custom inspection function on Objects via .inspect()#

Type: Documentation-only

Using a property named inspect on an object to specify a custom inspection function for util.inspect() is deprecated. Use util.inspect.custom instead. For backwards compatibility with Node.js prior to version 6.4.0, both may be specified.

DEP0080: path._makeLong()#

Type: Documentation-only

The internal path._makeLong() was not intended for public use. However, userland modules have found it useful. The internal API has been deprecated and replaced with an identical, public path.toNamespacedPath() method.

DEP0081: fs.truncate() using a file descriptor#

Type: Runtime

fs.truncate() fs.truncateSync() usage with a file descriptor has been deprecated. Please use fs.ftruncate() or fs.ftruncateSync() to work with file descriptors.

DEP0082: REPLServer.prototype.memory()#

Type: Runtime

REPLServer.prototype.memory() is a function only necessary for the internal mechanics of the REPLServer itself, and is therefore not necessary in user space.

DEP0083: Disabling ECDH by setting ecdhCurve to false#

Type: Runtime

The ecdhCurve option to tls.createSecureContext() and tls.TLSSocket could be set to false to disable ECDH entirely on the server only. This mode is deprecated in preparation for migrating to OpenSSL 1.1.0 and consistency with the client. Use the ciphers parameter instead.

DEP0085: AsyncHooks Sensitive API#

Type: Runtime

The AsyncHooks Sensitive API was never documented and had various of minor issues, see https://github.com/nodejs/node/issues/15572. Use the AsyncResource API instead.

DEP0086: Remove runInAsyncIdScope#

Type: Runtime

runInAsyncIdScope doesn't emit the before or after event and can thus cause a lot of issues. See https://github.com/nodejs/node/issues/14328 for more details.

DEP0089: require('assert')#

Type: Documentation-only

Importing assert directly is not recommended as the exposed functions will use loose equality checks. Use require('assert').strict instead. The API is the same as the legacy assert but it will always use strict equality checks.

DEP0098: AsyncHooks Embedder AsyncResource.emit<Before,After> APIs#

Type: Runtime

The embedded API provided by AsyncHooks exposes emit<Before,After> methods which are very easy to use incorrectly which can lead to unrecoverable errors.

Use asyncResource.runInAsyncScope() API instead which provides a much safer, and more convenient, alternative. See https://github.com/nodejs/node/pull/18513 for more details.