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nodejs/doc/api/globals.md
Gus Caplan 9f1282d536
lib: move queueMicrotask to stable
PR-URL: https://github.com/nodejs/node/pull/25594
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Yuta Hiroto <hello@hiroppy.me>
2019-03-08 08:19:38 -06:00

254 lines
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# Global Objects
<!--introduced_in=v0.10.0-->
<!-- type=misc -->
These objects are available in all modules. The following variables may appear
to be global but are not. They exist only in the scope of modules, see the
[module system documentation][]:
- [`__dirname`][]
- [`__filename`][]
- [`exports`][]
- [`module`][]
- [`require()`][]
The objects listed here are specific to Node.js. There are a number of
[built-in objects][] that are part of the JavaScript language itself, which are
also globally accessible.
## Class: Buffer
<!-- YAML
added: v0.1.103
-->
<!-- type=global -->
* {Function}
Used to handle binary data. See the [buffer section][].
## \_\_dirname
This variable may appear to be global but is not. See [`__dirname`].
## \_\_filename
This variable may appear to be global but is not. See [`__filename`].
## clearImmediate(immediateObject)
<!-- YAML
added: v0.9.1
-->
<!--type=global-->
[`clearImmediate`] is described in the [timers][] section.
## clearInterval(intervalObject)
<!-- YAML
added: v0.0.1
-->
<!--type=global-->
[`clearInterval`] is described in the [timers][] section.
## clearTimeout(timeoutObject)
<!-- YAML
added: v0.0.1
-->
<!--type=global-->
[`clearTimeout`] is described in the [timers][] section.
## console
<!-- YAML
added: v0.1.100
-->
<!-- type=global -->
* {Object}
Used to print to stdout and stderr. See the [`console`][] section.
## exports
This variable may appear to be global but is not. See [`exports`].
## global
<!-- YAML
added: v0.1.27
-->
<!-- type=global -->
* {Object} The global namespace object.
In browsers, the top-level scope is the global scope. This means that
within the browser `var something` will define a new global variable. In
Node.js this is different. The top-level scope is not the global scope;
`var something` inside a Node.js module will be local to that module.
## module
This variable may appear to be global but is not. See [`module`].
## process
<!-- YAML
added: v0.1.7
-->
<!-- type=global -->
* {Object}
The process object. See the [`process` object][] section.
## queueMicrotask(callback)
<!-- YAML
added: v11.0.0
-->
<!-- type=global -->
* `callback` {Function} Function to be queued.
The `queueMicrotask()` method queues a microtask to invoke `callback`. If
`callback` throws an exception, the [`process` object][] `'uncaughtException'`
event will be emitted.
The microtask queue is managed by V8 and may be used in a similar manner to
the [`process.nextTick()`][] queue, which is managed by Node.js. The
`process.nextTick()` queue is always processed before the microtask queue
within each turn of the Node.js event loop.
```js
// Here, `queueMicrotask()` is used to ensure the 'load' event is always
// emitted asynchronously, and therefore consistently. Using
// `process.nextTick()` here would result in the 'load' event always emitting
// before any other promise jobs.
DataHandler.prototype.load = async function load(key) {
const hit = this._cache.get(url);
if (hit !== undefined) {
queueMicrotask(() => {
this.emit('load', hit);
});
return;
}
const data = await fetchData(key);
this._cache.set(url, data);
this.emit('load', data);
};
```
## require()
This variable may appear to be global but is not. See [`require()`].
## setImmediate(callback[, ...args])
<!-- YAML
added: v0.9.1
-->
<!-- type=global -->
[`setImmediate`] is described in the [timers][] section.
## setInterval(callback, delay[, ...args])
<!-- YAML
added: v0.0.1
-->
<!-- type=global -->
[`setInterval`] is described in the [timers][] section.
## setTimeout(callback, delay[, ...args])
<!-- YAML
added: v0.0.1
-->
<!-- type=global -->
[`setTimeout`] is described in the [timers][] section.
## TextDecoder
<!-- YAML
added: v11.0.0
-->
<!-- type=global -->
The WHATWG `TextDecoder` class. See the [`TextDecoder`][] section.
## TextEncoder
<!-- YAML
added: v11.0.0
-->
<!-- type=global -->
The WHATWG `TextEncoder` class. See the [`TextEncoder`][] section.
## URL
<!-- YAML
added: v10.0.0
-->
<!-- type=global -->
The WHATWG `URL` class. See the [`URL`][] section.
## URLSearchParams
<!-- YAML
added: v10.0.0
-->
<!-- type=global -->
The WHATWG `URLSearchParams` class. See the [`URLSearchParams`][] section.
## WebAssembly
<!-- YAML
added: v8.0.0
-->
<!-- type=global -->
* {Object}
The object that acts as the namespace for all W3C
[WebAssembly][webassembly-org] related functionality. See the
[Mozilla Developer Network][webassembly-mdn] for usage and compatibility.
[`TextDecoder`]: util.html#util_class_util_textdecoder
[`TextEncoder`]: util.html#util_class_util_textencoder
[`URLSearchParams`]: url.html#url_class_urlsearchparams
[`URL`]: url.html#url_class_url
[`__dirname`]: modules.html#modules_dirname
[`__filename`]: modules.html#modules_filename
[`clearImmediate`]: timers.html#timers_clearimmediate_immediate
[`clearInterval`]: timers.html#timers_clearinterval_timeout
[`clearTimeout`]: timers.html#timers_cleartimeout_timeout
[`console`]: console.html
[`exports`]: modules.html#modules_exports
[`module`]: modules.html#modules_module
[`process.nextTick()`]: process.html#process_process_nexttick_callback_args
[`process` object]: process.html#process_process
[`require()`]: modules.html#modules_require_id
[`setImmediate`]: timers.html#timers_setimmediate_callback_args
[`setInterval`]: timers.html#timers_setinterval_callback_delay_args
[`setTimeout`]: timers.html#timers_settimeout_callback_delay_args
[buffer section]: buffer.html
[built-in objects]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects
[module system documentation]: modules.html
[timers]: timers.html
[webassembly-mdn]: https://developer.mozilla.org/en-US/docs/WebAssembly
[webassembly-org]: https://webassembly.org