WindowOrWorkerGlobalScope.queueMicrotask()

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句法
范例
When queueMicrotask() isn't available
规范
浏览器兼容性
另请参阅
相关话题

queueMicrotask() method, which is exposed on the Window or Worker interface, queues a microtask to be executed at a safe time prior to control returning to the browser's event loop. The microtask is a short function which will run after the current task has completed its work and when there is no other code waiting to be run before control of the execution context is returned to the browser's event loop.

This lets your code run without interfering with any other, potentially higher priority, code that is pending, but before the browser regains control over the execution context, potentially depending on work you need to complete. You can learn more about how to use microtasks and why you might choose to do so in our microtask guide .

The importance of microtasks comes in its ability to perform tasks asynchronously but in a specific order. See Using microtasks in JavaScript with queueMicrotask() 了解更多细节。

Microtasks are especially useful for libraries and frameworks that need to perform final cleanup or other just-before-rendering tasks.

queueMicrotask() is exposed on the WindowOrWorkerGlobalScope 混合。

句法

scope.queueMicrotask(function);

参数

function: function to be executed when the browser engine determines it is safe to call your code. Enqueued microtasks are executed after all pending tasks have completed but before yielding control to the browser's event loop.

返回值

undefined .

范例

self.queueMicrotask(() => {
  // function contents here
})

Taken from the queueMicrotask spec :

MyElement.prototype.loadData = function (url) {
  if (this._cache[url]) {
    queueMicrotask(() => {
      this._setData(this._cache[url]);
      this.dispatchEvent(new Event("load"));
    });
  } else {
    fetch(url).then(res => res.arrayBuffer()).then(data => {
      this._cache[url] = data;
      this._setData(data);
      this.dispatchEvent(new Event("load"));
    });
  }
};

When queueMicrotask() isn't available

The code below is basically a monkey-patch for queueMicrotask() for modern engines. It creates a microtask by using a promise that resolves immediately.

if (typeof window.queueMicrotask !== "function") {
  window.queueMicrotask = function (callback) {
    Promise.resolve()
      .then(callback)
      .catch(e => setTimeout(() => { throw e; })); // report exceptions
  };
}

规范

规范	状态	注释
HTML 实时标准 The definition of 'self.queueMicrotask()' in that specification.	实时标准	初始定义

浏览器兼容性

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

NOTE: data on this has been submitted; just waiting on it to be reviewed, merged, and for a new data release before it will show up here. See https://github.com/mdn/browser-compat-data/pull/4754 for PR. 更新 GitHub 上的兼容性数据

	桌面						移动
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`queueMicrotask`	Chrome 71	Edge 79	Firefox 69	IE No	Opera 58	Safari 12.1	WebView Android 71	Chrome Android 71	Firefox Android No	Opera Android 50	Safari iOS 12.2	Samsung Internet Android 10.0

图例

完整支持
不支持

另请参阅

Using microtasks in JavaScript with queueMicrotask()
异步 JavaScript
queueMicrotask explainer
Tasks, microtasks, queues and schedules by Jake Archibald

元数据

最后修改： May 4, 2020

在此页

句法

参数

返回值

范例

When queueMicrotask() isn't available

规范

浏览器兼容性

图例

另请参阅

相关话题