# Deprecated APIs




Node.js may deprecate APIs for any of the following reasons:

* Use of the API is unsafe.
* An improved alternative API is available.
* 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](#deprecations_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 when functionality is or will soon be removed
from Node.js.

## Revoking deprecations

Occasionally, the deprecation of an API may be reversed. 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: End-of-Life

The `CryptoStream.prototype.readyState` property was removed.

### DEP0005: `Buffer()` constructor


Type: Runtime (supports [`--pending-deprecation`][])

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

As an alternative, use one of the following methods of constructing `Buffer`
objects:

* [`Buffer.alloc(size[, fill[, encoding]])`][alloc]: Create a `Buffer` with
  *initialized* memory.
* [`Buffer.allocUnsafe(size)`][alloc_unsafe_size]: Create a `Buffer` with
  *uninitialized* memory.
* [`Buffer.allocUnsafeSlow(size)`][]: Create a `Buffer` with *uninitialized*
   memory.
* [`Buffer.from(array)`][]: Create a `Buffer` with a copy of `array`
* [`Buffer.from(arrayBuffer[, byteOffset[, length]])`][from_arraybuffer] -
  Create a `Buffer` that wraps the given `arrayBuffer`.
* [`Buffer.from(buffer)`][]: Create a `Buffer` that copies `buffer`.
* [`Buffer.from(string[, encoding])`][from_string_encoding]: Create a `Buffer`
  that copies `string`.

Without `--pending-deprecation`, runtime warnings occur only for code not in
`node_modules`. This means there will not be deprecation warnings for
`Buffer()` usage in dependencies. With `--pending-deprecation`, a runtime
warning results no matter where the `Buffer()` usage occurs.

### DEP0006: `child_process` `options.customFds`


Type: End-of-Life

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 is 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: Runtime

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
`digest` set to `undefined` will throw a `TypeError`.

Beginning in Node.js v11.0.0, calling these functions with `digest` set to
`null` will print a deprecation warning to align with the behavior when `digest`
is `undefined`.

### DEP0010: `crypto.createCredentials`


Type: End-of-Life

The `crypto.createCredentials()` API was removed. Please use
[`tls.createSecureContext()`][] instead.

### DEP0011: `crypto.Credentials`


Type: End-of-Life

The `crypto.Credentials` class was removed. Please use [`tls.SecureContext`][]
instead.

### DEP0012: `Domain.dispose`


Type: End-of-Life

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

### DEP0013: `fs` asynchronous function without callback


Type: End-of-Life

Calling an asynchronous function without a callback throws a `TypeError`
in Node.js 10.0.0 onwards. See <https://github.com/nodejs/node/pull/12562>.

### 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 are 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`](https://github.com/tc39/proposal-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: End-of-Life

In certain cases, `require('.')` could resolve outside the package directory.
This behavior has been removed.

### DEP0020: `Server.connections`


Type: Runtime

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

### DEP0021: `Server.listenFD`


Type: End-of-Life

The `Server.listenFD()` method was deprecated and removed. 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: End-of-Life

The `os.getNetworkInterfaces()` method is deprecated. Please use the
[`os.networkInterfaces()`][] method instead.

### DEP0024: `REPLServer.prototype.convertToContext()`


Type: End-of-Life

The `REPLServer.prototype.convertToContext()` API has been removed.

### DEP0025: `require('sys')`


Type: Runtime

The `sys` module is deprecated. Please use the [`util`][] module instead.

### DEP0026: `util.print()`


Type: End-of-Life

`util.print()` has been removed. Please use [`console.log()`][] instead.

### DEP0027: `util.puts()`


Type: End-of-Life

`util.puts()` has been removed. Please use [`console.log()`][] instead.

### DEP0028: `util.debug()`


Type: End-of-Life

`util.debug()` has been removed. Please use [`console.error()`][] instead.

### DEP0029: `util.error()`


Type: End-of-Life

`util.error()` has been removed. Please use [`console.error()`][] instead.

### DEP0030: `SlowBuffer`


Type: Documentation-only

The [`SlowBuffer`][] class is 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 is
deprecated. Please use [`emitter.listenerCount(eventName)`][] instead.

### DEP0034: `fs.exists(path, callback)`


Type: Documentation-only

The [`fs.exists(path, callback)`][] API is 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 is deprecated.

### DEP0036: `fs.lchmodSync(path, mode)`


Type: Documentation-only

The [`fs.lchmodSync(path, mode)`][] API is deprecated.

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


Type: Deprecation revoked

The [`fs.lchown(path, uid, gid, callback)`][] API was deprecated. The
deprecation was revoked because the requisite supporting APIs were added in
libuv.

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


Type: Deprecation revoked

The [`fs.lchownSync(path, uid, gid)`][] API was deprecated. The deprecation was
revoked because the requisite supporting APIs were added in libuv.

### DEP0039: `require.extensions`


Type: Documentation-only

The [`require.extensions`][] property is deprecated.

### DEP0040: `punycode` module


Type: Documentation-only

The [`punycode`][] module is deprecated. Please use a userland alternative
instead.

### DEP0041: `NODE_REPL_HISTORY_FILE` environment variable


Type: End-of-Life

The `NODE_REPL_HISTORY_FILE` environment variable was removed. Please use
`NODE_REPL_HISTORY` instead.

### DEP0042: `tls.CryptoStream`


Type: End-of-Life

The [`tls.CryptoStream`][] class was removed. Please use
[`tls.TLSSocket`][] instead.

### DEP0043: `tls.SecurePair`


Type: Documentation-only

The [`tls.SecurePair`][] class is deprecated. Please use
[`tls.TLSSocket`][] instead.

### DEP0044: `util.isArray()`


Type: Documentation-only

The [`util.isArray()`][] API is deprecated. Please use `Array.isArray()`
instead.

### DEP0045: `util.isBoolean()`


Type: Documentation-only

The [`util.isBoolean()`][] API is deprecated.

### DEP0046: `util.isBuffer()`


Type: Documentation-only

The [`util.isBuffer()`][] API is deprecated. Please use
[`Buffer.isBuffer()`][] instead.

### DEP0047: `util.isDate()`


Type: Documentation-only

The [`util.isDate()`][] API is deprecated.

### DEP0048: `util.isError()`


Type: Documentation-only

The [`util.isError()`][] API is deprecated.

### DEP0049: `util.isFunction()`


Type: Documentation-only

The [`util.isFunction()`][] API is deprecated.

### DEP0050: `util.isNull()`


Type: Documentation-only

The [`util.isNull()`][] API is deprecated.

### DEP0051: `util.isNullOrUndefined()`


Type: Documentation-only

The [`util.isNullOrUndefined()`][] API is deprecated.

### DEP0052: `util.isNumber()`


Type: Documentation-only

The [`util.isNumber()`][] API is deprecated.

### DEP0053 `util.isObject()`


Type: Documentation-only

The [`util.isObject()`][] API is deprecated.

### DEP0054: `util.isPrimitive()`


Type: Documentation-only

The [`util.isPrimitive()`][] API is deprecated.

### DEP0055: `util.isRegExp()`


Type: Documentation-only

The [`util.isRegExp()`][] API is deprecated.

### DEP0056: `util.isString()`


Type: Documentation-only

The [`util.isString()`][] API is deprecated.

### DEP0057: `util.isSymbol()`


Type: Documentation-only

The [`util.isSymbol()`][] API is deprecated.

### DEP0058: `util.isUndefined()`


Type: Documentation-only

The [`util.isUndefined()`][] API is deprecated.

### DEP0059: `util.log()`


Type: Documentation-only

The [`util.log()`][] API is deprecated.

### DEP0060: `util._extend()`


Type: Documentation-only

The [`util._extend()`][] API is deprecated.

### DEP0061: `fs.SyncWriteStream`


Type: End-of-Life

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

### DEP0062: `node --debug`


Type: End-of-Life

`--debug` activates the legacy V8 debugger interface, which was 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 is
deprecated. Please use `ServerResponse.prototype.writeHead()` instead.

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: End-of-Life

The `repl` module's `REPL_MODE_MAGIC` constant, used for `replMode` option, has
been removed. Its behavior has been functionally identical to that of
`REPL_MODE_SLOPPY` since Node.js 6.0.0, 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 value, `magic`, is also
removed. Please use `sloppy` instead.

### DEP0066: `OutgoingMessage.prototype._headers, OutgoingMessage.prototype._headerNames`


Type: Runtime

The `http` module `OutgoingMessage.prototype._headers` and
`OutgoingMessage.prototype._headerNames` properties are deprecated. Use one of
the public methods (e.g. `OutgoingMessage.prototype.getHeader()`,
`OutgoingMessage.prototype.getHeaders()`,
`OutgoingMessage.prototype.getHeaderNames()`,
`OutgoingMessage.prototype.hasHeader()`,
`OutgoingMessage.prototype.removeHeader()`,
`OutgoingMessage.prototype.setHeader()`) for working with outgoing headers.

The `OutgoingMessage.prototype._headers` and
`OutgoingMessage.prototype._headerNames` properties were never documented as
officially supported properties.

### DEP0067: `OutgoingMessage.prototype._renderHeaders`


Type: Documentation-only

The `http` module `OutgoingMessage.prototype._renderHeaders()` API is
deprecated.

The `OutgoingMessage.prototype._renderHeaders` property 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: End-of-Life

DebugContext has been removed in V8 and is not available in Node.js 10+.

DebugContext was an experimental API.

### DEP0070: `async_hooks.currentId()`


Type: End-of-Life

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

This 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.

This 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.

This change was made while `async_hooks` was an experimental API.

### DEP0073: Several internal properties of `net.Server`


Type: End-of-Life

Accessing several internal, undocumented properties of `net.Server` instances
with inappropriate names is deprecated.

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:

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

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

```console
> 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()` is deprecated.

The `Module._debug()` function 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: End-of-Life

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 backward 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 is 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 is
deprecated. Please use `fs.ftruncate()` or `fs.ftruncateSync()` to work with
file descriptors.

### DEP0082: `REPLServer.prototype.memory()`


Type: Runtime

`REPLServer.prototype.memory()` is only necessary for the internal mechanics of
the `REPLServer` itself. Do not use this function.

### DEP0083: Disabling ECDH by setting `ecdhCurve` to `false`


Type: End-of-Life.

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

### DEP0084: requiring bundled internal dependencies

Type: End-of-Life

Since Node.js versions 4.4.0 and 5.2.0, several modules only intended for
internal usage were mistakenly exposed to user code through `require()`. These
modules were:

* `v8/tools/codemap`
* `v8/tools/consarray`
* `v8/tools/csvparser`
* `v8/tools/logreader`
* `v8/tools/profile_view`
* `v8/tools/profile`
* `v8/tools/SourceMap`
* `v8/tools/splaytree`
* `v8/tools/tickprocessor-driver`
* `v8/tools/tickprocessor`
* `node-inspect/lib/_inspect` (from 7.6.0)
* `node-inspect/lib/internal/inspect_client` (from 7.6.0)
* `node-inspect/lib/internal/inspect_repl` (from 7.6.0)

The `v8/*` modules do not have any exports, and if not imported in a specific
order would in fact throw errors. As such there are virtually no legitimate use
cases for importing them through `require()`.

On the other hand, `node-inspect` may be installed locally through a package
manager, as it is published on the npm registry under the same name. No source
code modification is necessary if that is done.

### DEP0085: AsyncHooks sensitive API

Type: End-of-Life

The AsyncHooks sensitive API was never documented and had various minor issues.
Use the `AsyncResource` API instead. See
<https://github.com/nodejs/node/issues/15572>.

### DEP0086: Remove `runInAsyncIdScope`


Type: End-of-Life

`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>.

### DEP0089: `require('assert')`


Type: Deprecation revoked

Importing assert directly was not recommended as the exposed functions use
loose equality checks. The deprecation was revoked because use of the `assert`
module is not discouraged, and the deprecation caused developer confusion.

### DEP0090: Invalid GCM authentication tag lengths

Type: End-of-Life

Node.js used to support all GCM authentication tag lengths which are accepted by
OpenSSL when calling [`decipher.setAuthTag()`][]. Beginning with Node.js
v11.0.0, only authentication tag lengths of 128, 120, 112, 104, 96, 64, and 32
bits are allowed. Authentication tags of other lengths are invalid per
[NIST SP 800-38D][].

### DEP0091: `crypto.DEFAULT_ENCODING`


Type: Runtime

The [`crypto.DEFAULT_ENCODING`][] property is deprecated.

### DEP0092: Top-level `this` bound to `module.exports`


Type: Documentation-only

Assigning properties to the top-level `this` as an alternative
to `module.exports` is deprecated. Developers should use `exports`
or `module.exports` instead.

### DEP0093: `crypto.fips` is deprecated and replaced.


Type: Documentation-only

The [`crypto.fips`][] property is deprecated. Please use `crypto.setFips()`
and `crypto.getFips()` instead.

### DEP0094: Using `assert.fail()` with more than one argument.


Type: Runtime

Using `assert.fail()` with more than one argument is deprecated. Use
`assert.fail()` with only one argument or use a different `assert` module
method.

### DEP0095: `timers.enroll()`


Type: Runtime

`timers.enroll()` is deprecated. Please use the publicly documented
[`setTimeout()`][] or [`setInterval()`][] instead.

### DEP0096: `timers.unenroll()`


Type: Runtime

`timers.unenroll()` is deprecated. Please use the publicly documented
[`clearTimeout()`][] or [`clearInterval()`][] instead.

### DEP0097: `MakeCallback` with `domain` property


Type: Runtime

Users of `MakeCallback` that add the `domain` property to carry context,
should start using the `async_context` variant of `MakeCallback` or
`CallbackScope`, or the high-level `AsyncResource` class.

### DEP0098: AsyncHooks embedder `AsyncResource.emitBefore` and `AsyncResource.emitAfter` APIs


Type: End-of-Life

The embedded API provided by AsyncHooks exposes `.emitBefore()` and
`.emitAfter()` 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>.

### DEP0099: Async context-unaware `node::MakeCallback` C++ APIs


Type: Compile-time

Certain versions of `node::MakeCallback` APIs available to native modules are
deprecated. Please use the versions of the API that accept an `async_context`
parameter.

### DEP0100: `process.assert()`


Type: Runtime

`process.assert()` is deprecated. Please use the [`assert`][] module instead.

This was never a documented feature.

### DEP0101: `--with-lttng`


Type: End-of-Life

The `--with-lttng` compile-time option has been removed.

### DEP0102: Using `noAssert` in `Buffer#(read|write)` operations.


Type: End-of-Life

Using the `noAssert` argument has no functionality anymore. All input is going
to be verified, no matter if it is set to true or not. Skipping the verification
could lead to hard to find errors and crashes.

### DEP0103: `process.binding('util').is[...]` typechecks


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

Using `process.binding()` in general should be avoided. The type checking
methods in particular can be replaced by using [`util.types`][].

This deprecation has been superseded by the deprecation of the
`process.binding()` API ([DEP0111](#DEP0111)).

### DEP0104: `process.env` string coercion


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

When assigning a non-string property to [`process.env`][], the assigned value is
implicitly converted to a string. This behavior is deprecated if the assigned
value is not a string, boolean, or number. In the future, such assignment may
result in a thrown error. Please convert the property to a string before
assigning it to `process.env`.

### DEP0105: `decipher.finaltol`


Type: End-of-Life

`decipher.finaltol()` has never been documented and was an alias for
[`decipher.final()`][]. This API has been removed, and it is recommended to use
[`decipher.final()`][] instead.

### DEP0106: `crypto.createCipher` and `crypto.createDecipher`


Type: Runtime

Using [`crypto.createCipher()`][] and [`crypto.createDecipher()`][] should be
avoided as they use a weak key derivation function (MD5 with no salt) and static
initialization vectors. It is recommended to derive a key using
[`crypto.pbkdf2()`][] or [`crypto.scrypt()`][] and to use
[`crypto.createCipheriv()`][] and [`crypto.createDecipheriv()`][] to obtain the
[`Cipher`][] and [`Decipher`][] objects respectively.

### DEP0107: `tls.convertNPNProtocols()`

Type: End-of-Life

This was an undocumented helper function not intended for use outside Node.js
core and obsoleted by the removal of NPN (Next Protocol Negotiation) support.

### DEP0108: `zlib.bytesRead`


Type: Runtime

Deprecated alias for [`zlib.bytesWritten`][]. This original name was chosen
because it also made sense to interpret the value as the number of bytes
read by the engine, but is inconsistent with other streams in Node.js that
expose values under these names.

### DEP0109: `http`, `https`, and `tls` support for invalid URLs


Type: Runtime

Some previously supported (but strictly invalid) URLs were accepted through the
[`http.request()`][], [`http.get()`][], [`https.request()`][],
[`https.get()`][], and [`tls.checkServerIdentity()`][] APIs because those were
accepted by the legacy `url.parse()` API. The mentioned APIs now use the WHATWG
URL parser that requires strictly valid URLs. Passing an invalid URL is
deprecated and support will be removed in the future.

### DEP0110: `vm.Script` cached data


Type: Documentation-only

The `produceCachedData` option is deprecated. Use
[`script.createCachedData()`][] instead.

### DEP0111: `process.binding()`


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

`process.binding()` is for use by Node.js internal code only.

### DEP0112: `dgram` private APIs


Type: Runtime

The `dgram` module previously contained several APIs that were never meant to
accessed outside of Node.js core: `Socket.prototype._handle`,
`Socket.prototype._receiving`, `Socket.prototype._bindState`,
`Socket.prototype._queue`, `Socket.prototype._reuseAddr`,
`Socket.prototype._healthCheck()`, `Socket.prototype._stopReceiving()`, and
`dgram._createSocketHandle()`.

### DEP0113: `Cipher.setAuthTag()`, `Decipher.getAuthTag()`


Type: End-of-Life

`Cipher.setAuthTag()` and `Decipher.getAuthTag()` are no longer available. They
were never documented and would throw when called.

### DEP0114: `crypto._toBuf()`


Type: End-of-Life

The `crypto._toBuf()` function was not designed to be used by modules outside
of Node.js core and was removed.

### DEP0115: `crypto.prng()`, `crypto.pseudoRandomBytes()`, `crypto.rng()`


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

In recent versions of Node.js, there is no difference between
[`crypto.randomBytes()`][] and `crypto.pseudoRandomBytes()`. The latter is
deprecated along with the undocumented aliases `crypto.prng()` and
`crypto.rng()` in favor of [`crypto.randomBytes()`][] and may be removed in a
future release.

### DEP0116: Legacy URL API

Type: Documentation-only

The [Legacy URL API][] is deprecated. This includes [`url.format()`][],
[`url.parse()`][], [`url.resolve()`][], and the [legacy `urlObject`][]. Please
use the [WHATWG URL API][] instead.

### DEP0117: Native crypto handles

Type: End-of-Life

Previous versions of Node.js exposed handles to internal native objects through
the `_handle` property of the `Cipher`, `Decipher`, `DiffieHellman`,
`DiffieHellmanGroup`, `ECDH`, `Hash`, `Hmac`, `Sign`, and `Verify` classes.
The `_handle` property has been removed because improper use of the native
object can lead to crashing the application.

### DEP0118: `dns.lookup()` support for a falsy host name


Type: Runtime

Previous versions of Node.js supported `dns.lookup()` with a falsy host name
like `dns.lookup(false)` due to backward compatibility.
This behavior is undocumented and is thought to be unused in real world apps.
It will become an error in future versions of Node.js.

### DEP0119: `process.binding('uv').errname()` private API


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

`process.binding('uv').errname()` is deprecated. Please use
[`util.getSystemErrorName()`][] instead.

### DEP0120: Windows Performance Counter support

Type: End-of-Life

Windows Performance Counter support has been removed from Node.js. The
undocumented `COUNTER_NET_SERVER_CONNECTION()`,
`COUNTER_NET_SERVER_CONNECTION_CLOSE()`, `COUNTER_HTTP_SERVER_REQUEST()`,
`COUNTER_HTTP_SERVER_RESPONSE()`, `COUNTER_HTTP_CLIENT_REQUEST()`, and
`COUNTER_HTTP_CLIENT_RESPONSE()` functions have been deprecated.

### DEP0121: `net._setSimultaneousAccepts()`


Type: Runtime

The undocumented `net._setSimultaneousAccepts()` function was originally
intended for debugging and performance tuning when using the `child_process`
and `cluster` modules on Windows. The function is not generally useful and
is being removed. See discussion here:
<https://github.com/nodejs/node/issues/18391>

### DEP0122: `tls` `Server.prototype.setOptions()`


Type: Runtime

Please use `Server.prototype.setSecureContext()` instead.

### DEP0123: setting the TLS ServerName to an IP address

Type: Runtime

Setting the TLS ServerName to an IP address is not permitted by
[RFC 6066][]. This will be ignored in a future version.

### DEP0124: using `REPLServer.rli`

Type: Runtime

This property is a reference to the instance itself.

### DEP0125: `require('_stream_wrap')`


Type: Runtime

The `_stream_wrap` module is deprecated.

### DEP0126: `timers.active()`


Type: Runtime

The previously undocumented `timers.active()` is deprecated.
Please use the publicly documented [`timeout.refresh()`][] instead.
If re-referencing the timeout is necessary, [`timeout.ref()`][] can be used
with no performance impact since Node.js 10.

### DEP0127: `timers._unrefActive()`


Type: Runtime

The previously undocumented and "private" `timers._unrefActive()` is deprecated.
Please use the publicly documented [`timeout.refresh()`][] instead.
If unreferencing the timeout is necessary, [`timeout.unref()`][] can be used
with no performance impact since Node.js 10.

### DEP0128: modules with an invalid `main` entry and an `index.js` file


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

Modules that have an invalid `main` entry (e.g., `./does-not-exist.js`) and
also have an `index.js` file in the top level directory will resolve the
`index.js` file. That is deprecated and is going to throw an error in future
Node.js versions.

### DEP0129: `ChildProcess._channel`


Type: Documentation-only

The `_channel` property of child process objects returned by `spawn()` and
similar functions is not intended for public use. Use `ChildProcess.channel`
instead.

### DEP0130: `Module.createRequireFromPath()`


Type: Documentation-only

Module.createRequireFromPath() is deprecated. Please use [`module.createRequire()`][] instead.

### DEP0131: Legacy HTTP parser

Type: Runtime

The legacy HTTP parser, used by default in versions of Node.js prior to 12.0.0,
is deprecated. This deprecation applies to users of the
[`--http-parser=legacy`][] command-line flag.

### DEP0132: `worker.terminate()` with callback


Type: Runtime

Passing a callback to [`worker.terminate()`][] is deprecated. Use the returned
`Promise` instead, or a listener to the worker’s `'exit'` event.

### DEP0133: `http` `connection`


Type: Documentation-only

Prefer [`response.socket`][] over [`response.connection`][] and
[`request.socket`][] over [`request.connection`][].

### DEP0134: `process._tickCallback`

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

The `process._tickCallback` property was never documented as
an officially supported API.

### DEP0136: `http` `finished`


Type: Documentation-only

[`response.finished`][] indicates whether [`response.end()`][] has been
called, not whether `'finish'` has been emitted and the underlying data
is flushed.

Use [`response.writableFinished`][] or [`response.writableEnded`][]
accordingly instead to avoid the ambigiuty.

To maintain existing behaviour `response.finished` should be replaced with
`response.writableEnded`.

### DEP0139: `process.umask()` with no arguments


Type: Documentation-only

Calling `process.umask()` with no argument causes the process-wide umask to be
written twice. This introduces a race condition between threads, and is a
potential security vulnerability. There is no safe, cross-platform alternative
API.

### DEP0144: `module.parent`


Type: Documentation-only

A CommonJS module can access the first module that required it using
`module.parent`. This feature is deprecated because it does not work
consistently in the presence of ECMAScript modules and because it gives an
inaccurate representation of the CommonJS module graph.

Some modules use it to check if they are the entry point of the current process.
Instead, it is recommended to compare `require.main` and `module`:

```js
if (require.main === module) {
  // Code section that will run only if current file is the entry point.
}
```

When looking for the CommonJS modules that have required the current one,
`require.cache` and `module.children` can be used:

```js
const moduleParents = Object.values(require.cache)
  .filter((m) => m.children.includes(module));
```

[`--http-parser=legacy`]: cli.html#cli_http_parser_library
[`--pending-deprecation`]: cli.html#cli_pending_deprecation
[`--throw-deprecation`]: cli.html#cli_throw_deprecation
[`Buffer.allocUnsafeSlow(size)`]: buffer.html#buffer_static_method_buffer_allocunsafeslow_size
[`Buffer.from(array)`]: buffer.html#buffer_static_method_buffer_from_array
[`Buffer.from(buffer)`]: buffer.html#buffer_static_method_buffer_from_buffer
[`Buffer.isBuffer()`]: buffer.html#buffer_static_method_buffer_isbuffer_obj
[`Cipher`]: crypto.html#crypto_class_cipher
[`Decipher`]: crypto.html#crypto_class_decipher
[`EventEmitter.listenerCount(emitter, eventName)`]: events.html#events_eventemitter_listenercount_emitter_eventname
[`REPLServer.clearBufferedCommand()`]: repl.html#repl_replserver_clearbufferedcommand
[`Server.connections`]: net.html#net_server_connections
[`Server.getConnections()`]: net.html#net_server_getconnections_callback
[`Server.listen({fd: <number>})`]: net.html#net_server_listen_handle_backlog_callback
[`SlowBuffer`]: buffer.html#buffer_class_slowbuffer
[`assert`]: assert.html
[`asyncResource.runInAsyncScope()`]: async_hooks.html#async_hooks_asyncresource_runinasyncscope_fn_thisarg_args
[`child_process`]: child_process.html
[`clearInterval()`]: timers.html#timers_clearinterval_timeout
[`clearTimeout()`]: timers.html#timers_cleartimeout_timeout
[`console.error()`]: console.html#console_console_error_data_args
[`console.log()`]: console.html#console_console_log_data_args
[`crypto.DEFAULT_ENCODING`]: crypto.html#crypto_crypto_default_encoding
[`crypto.createCipher()`]: crypto.html#crypto_crypto_createcipher_algorithm_password_options
[`crypto.createCipheriv()`]: crypto.html#crypto_crypto_createcipheriv_algorithm_key_iv_options
[`crypto.createDecipher()`]: crypto.html#crypto_crypto_createdecipher_algorithm_password_options
[`crypto.createDecipheriv()`]: crypto.html#crypto_crypto_createdecipheriv_algorithm_key_iv_options
[`crypto.fips`]: crypto.html#crypto_crypto_fips
[`crypto.pbkdf2()`]: crypto.html#crypto_crypto_pbkdf2_password_salt_iterations_keylen_digest_callback
[`crypto.randomBytes()`]: crypto.html#crypto_crypto_randombytes_size_callback
[`crypto.scrypt()`]: crypto.html#crypto_crypto_scrypt_password_salt_keylen_options_callback
[`decipher.final()`]: crypto.html#crypto_decipher_final_outputencoding
[`decipher.setAuthTag()`]: crypto.html#crypto_decipher_setauthtag_buffer
[`domain`]: domain.html
[`ecdh.setPublicKey()`]: crypto.html#crypto_ecdh_setpublickey_publickey_encoding
[`emitter.listenerCount(eventName)`]: events.html#events_emitter_listenercount_eventname
[`fs.access()`]: fs.html#fs_fs_access_path_mode_callback
[`fs.exists(path, callback)`]: fs.html#fs_fs_exists_path_callback
[`fs.lchmod(path, mode, callback)`]: fs.html#fs_fs_lchmod_path_mode_callback
[`fs.lchmodSync(path, mode)`]: fs.html#fs_fs_lchmodsync_path_mode
[`fs.lchown(path, uid, gid, callback)`]: fs.html#fs_fs_lchown_path_uid_gid_callback
[`fs.lchownSync(path, uid, gid)`]: fs.html#fs_fs_lchownsync_path_uid_gid
[`fs.read()`]: fs.html#fs_fs_read_fd_buffer_offset_length_position_callback
[`fs.readSync()`]: fs.html#fs_fs_readsync_fd_buffer_offset_length_position
[`fs.stat()`]: fs.html#fs_fs_stat_path_options_callback
[`http.get()`]: http.html#http_http_get_options_callback
[`http.request()`]: http.html#http_http_request_options_callback
[`https.get()`]: https.html#https_https_get_options_callback
[`https.request()`]: https.html#https_https_request_options_callback
[`module.createRequire()`]: module.html#module_module_createrequire_filename
[`os.networkInterfaces()`]: os.html#os_os_networkinterfaces
[`os.tmpdir()`]: os.html#os_os_tmpdir
[`process.env`]: process.html#process_process_env
[`punycode`]: punycode.html
[`require.extensions`]: modules.html#modules_require_extensions
[`request.socket`]: http.html#http_request_socket
[`request.connection`]: http.html#http_request_connection
[`response.socket`]: http.html#http_response_socket
[`response.connection`]: http.html#http_response_connection
[`response.end()`]: http.html#http_response_end_data_encoding_callback
[`response.finished`]: http.html#http_response_finished
[`response.writableFinished`]: http.html#http_response_writablefinished
[`response.writableEnded`]: http.html#http_response_writableended
[`script.createCachedData()`]: vm.html#vm_script_createcacheddata
[`setInterval()`]: timers.html#timers_setinterval_callback_delay_args
[`setTimeout()`]: timers.html#timers_settimeout_callback_delay_args
[`timeout.ref()`]: timers.html#timers_timeout_ref
[`timeout.refresh()`]: timers.html#timers_timeout_refresh
[`timeout.unref()`]: timers.html#timers_timeout_unref
[`tls.CryptoStream`]: tls.html#tls_class_tls_cryptostream
[`tls.SecureContext`]: tls.html#tls_tls_createsecurecontext_options
[`tls.SecurePair`]: tls.html#tls_class_tls_securepair
[`tls.TLSSocket`]: tls.html#tls_class_tls_tlssocket
[`tls.checkServerIdentity()`]: tls.html#tls_tls_checkserveridentity_hostname_cert
[`tls.createSecureContext()`]: tls.html#tls_tls_createsecurecontext_options
[`url.format()`]: url.html#url_url_format_urlobject
[`url.parse()`]: url.html#url_url_parse_urlstring_parsequerystring_slashesdenotehost
[`url.resolve()`]: url.html#url_url_resolve_from_to
[`util._extend()`]: util.html#util_util_extend_target_source
[`util.getSystemErrorName()`]: util.html#util_util_getsystemerrorname_err
[`util.inspect()`]: util.html#util_util_inspect_object_options
[`util.inspect.custom`]: util.html#util_util_inspect_custom
[`util.isArray()`]: util.html#util_util_isarray_object
[`util.isBoolean()`]: util.html#util_util_isboolean_object
[`util.isBuffer()`]: util.html#util_util_isbuffer_object
[`util.isDate()`]: util.html#util_util_isdate_object
[`util.isError()`]: util.html#util_util_iserror_object
[`util.isFunction()`]: util.html#util_util_isfunction_object
[`util.isNull()`]: util.html#util_util_isnull_object
[`util.isNullOrUndefined()`]: util.html#util_util_isnullorundefined_object
[`util.isNumber()`]: util.html#util_util_isnumber_object
[`util.isObject()`]: util.html#util_util_isobject_object
[`util.isPrimitive()`]: util.html#util_util_isprimitive_object
[`util.isRegExp()`]: util.html#util_util_isregexp_object
[`util.isString()`]: util.html#util_util_isstring_object
[`util.isSymbol()`]: util.html#util_util_issymbol_object
[`util.isUndefined()`]: util.html#util_util_isundefined_object
[`util.log()`]: util.html#util_util_log_string
[`util.types`]: util.html#util_util_types
[`util`]: util.html
[`worker.exitedAfterDisconnect`]: cluster.html#cluster_worker_exitedafterdisconnect
[`worker.terminate()`]: worker_threads.html#worker_threads_worker_terminate
[`zlib.bytesWritten`]: zlib.html#zlib_zlib_byteswritten
[Legacy URL API]: url.html#url_legacy_url_api
[NIST SP 800-38D]: https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf
[RFC 6066]: https://tools.ietf.org/html/rfc6066#section-3
[WHATWG URL API]: url.html#url_the_whatwg_url_api
[alloc]: buffer.html#buffer_static_method_buffer_alloc_size_fill_encoding
[alloc_unsafe_size]: buffer.html#buffer_static_method_buffer_allocunsafe_size
[from_arraybuffer]: buffer.html#buffer_static_method_buffer_from_arraybuffer_byteoffset_length
[from_string_encoding]: buffer.html#buffer_static_method_buffer_from_string_encoding
[legacy `urlObject`]: url.html#url_legacy_urlobject
