Node.js v16.20.2 文档

类：AbortController#>

¥Class: AbortController

用于在选定的基于 Promise 的 API 中触发取消信号的实用工具类。该 API 基于 Web API AbortController。

¥A utility class used to signal cancelation in selected Promise-based APIs. The API is based on the Web API AbortController.

const ac = new AbortController();

ac.signal.addEventListener('abort', () => console.log('Aborted!'),
                           { once: true });

ac.abort();

console.log(ac.signal.aborted);  // Prints True 拷贝

abortController.abort([reason])#>

• reason <any> 可选的原因，可在 AbortSignal 的 reason 属性中检索。

  ¥reason <any> An optional reason, retrievable on the AbortSignal's reason property.

触发中止信号，使 abortController.signal 触发 'abort' 事件。

¥Triggers the abort signal, causing the abortController.signal to emit the 'abort' event.

abortController.signal#>

• 类型：<AbortSignal>

  ¥Type: <AbortSignal>

类：AbortSignal#>

¥Class: AbortSignal

• 继承：<EventTarget>

  ¥Extends: <EventTarget>

AbortSignal 用于在调用 abortController.abort() 方法时通知监视器。

¥The AbortSignal is used to notify observers when the abortController.abort() method is called.

静态方法：AbortSignal.abort([reason])#>

¥Static method: AbortSignal.abort([reason])

• reason：<any>

• 返回：<AbortSignal>

  ¥Returns: <AbortSignal>

返回新的已中止的 AbortSignal。

¥Returns a new already aborted AbortSignal.

静态方法：AbortSignal.timeout(delay)#>

¥Static method: AbortSignal.timeout(delay)

• delay <number> 触发 AbortSignal 之前等待的毫秒数。

  ¥delay <number> The number of milliseconds to wait before triggering the AbortSignal.

返回新的 AbortSignal，其将在 delay 毫秒内中止。

¥Returns a new AbortSignal which will be aborted in delay milliseconds.

事件：'abort'#>

¥Event: 'abort'

当调用 abortController.abort() 方法时，则触发 'abort' 事件。使用单个对象参数调用回调，该对象具有被设置为 'abort' 的 type 属性：

¥The 'abort' event is emitted when the abortController.abort() method is called. The callback is invoked with a single object argument with a single type property set to 'abort':

const ac = new AbortController();

// Use either the onabort property...
ac.signal.onabort = () => console.log('aborted!');

// Or the EventTarget API...
ac.signal.addEventListener('abort', (event) => {
  console.log(event.type);  // Prints 'abort'
}, { once: true });

ac.abort(); 拷贝

与 AbortSignal 关联的 AbortController 只会触发一次 'abort' 事件。建议在添加 'abort' 事件监听器之前代码检查 abortSignal.aborted 属性是否为 false。

¥The AbortController with which the AbortSignal is associated will only ever trigger the 'abort' event once. We recommended that code check that the abortSignal.aborted attribute is false before adding an 'abort' event listener.

任何绑定到 AbortSignal 的事件监听器都应使用 { once: true } 选项（或者，如果使用 EventEmitter API 绑定监听器，则使用 once() 方法）以确保在处理 'abort' 事件后立即删除事件监听器。不这样做可能会导致内存泄漏。

¥Any event listeners attached to the AbortSignal should use the { once: true } option (or, if using the EventEmitter APIs to attach a listener, use the once() method) to ensure that the event listener is removed as soon as the 'abort' event is handled. Failure to do so may result in memory leaks.

abortSignal.aborted#>

• 类型：<boolean> 中止 AbortController 后为真。

  ¥Type: <boolean> True after the AbortController has been aborted.

abortSignal.onabort#>

• 类型：<Function>

  ¥Type: <Function>

可选的回调函数，可以由用户代码设置，以便当调用 abortController.abort() 函数时得到通知。

¥An optional callback function that may be set by user code to be notified when the abortController.abort() function has been called.

abortSignal.reason#>

• 类型：<any>

  ¥Type: <any>

当触发 AbortSignal 时指定的可选的原因。

¥An optional reason specified when the AbortSignal was triggered.

const ac = new AbortController();
ac.abort(new Error('boom!'));
console.log(ac.signal.reason);  // Error('boom!'); 拷贝

abortSignal.throwIfAborted()#>

如果 abortSignal.aborted 是 true，则抛出 abortSignal.reason。

¥If abortSignal.aborted is true, throws abortSignal.reason.

类：Buffer#>

¥Class: Buffer

• <Function>

用于处理二进制数据。参见 缓冲区。

¥Used to handle binary data. See the buffer section.

__dirname#>

此变量可能看起来是全局的，但实际上不是。参见 __dirname。

¥This variable may appear to be global but is not. See __dirname.

__filename#>

此变量可能看起来是全局的，但实际上不是。参见 __filename。

¥This variable may appear to be global but is not. See __filename.

atob(data)#>

buffer.atob() 的全局别名。

¥Global alias for buffer.atob().

btoa(data)#>

buffer.btoa() 的全局别名。

¥Global alias for buffer.btoa().

clearImmediate(immediateObject)#>

clearImmediate 在 定时器 部分中描述。

¥clearImmediate is described in the timers section.

clearInterval(intervalObject)#>

clearInterval 在 定时器 部分中描述。

¥clearInterval is described in the timers section.

clearTimeout(timeoutObject)#>

clearTimeout 在 定时器 部分中描述。

¥clearTimeout is described in the timers section.

console#>

• <Object>

用于打印到标准输出和标准错误。参阅 console 章节。

¥Used to print to stdout and stderr. See the console section.

Crypto#>

<Crypto> 的浏览器兼容实现。只有在编译 Node.js 二进制文件时包含对 node:crypto 模块的支持，此全局才可用。

¥A browser-compatible implementation of <Crypto>. This global is available only if the Node.js binary was compiled with including support for the node:crypto module.

crypto#>

网络加密 API 的浏览器兼容实现。

¥A browser-compatible implementation of the Web Crypto API.

CryptoKey#>

<CryptoKey> 的浏览器兼容实现。只有在编译 Node.js 二进制文件时包含对 node:crypto 模块的支持，此全局才可用。

¥A browser-compatible implementation of <CryptoKey>. This global is available only if the Node.js binary was compiled with including support for the node:crypto module.

CustomEvent#>

CustomEvent 网络应用接口 的浏览器兼容实现。

¥A browser-compatible implementation of the CustomEvent Web API.

Event#>

Event 类的浏览器兼容的实现。有关详细信息，请参阅 EventTarget 和 Event API。

¥A browser-compatible implementation of the Event class. See EventTarget and Event API for more details.

EventTarget#>

EventTarget 类的浏览器兼容的实现。有关详细信息，请参阅 EventTarget 和 Event API。

¥A browser-compatible implementation of the EventTarget class. See EventTarget and Event API for more details.

exports#>

此变量可能看起来是全局的，但实际上不是。参见 exports。

¥This variable may appear to be global but is not. See exports.

fetch#>

fetch() 函数的浏览器兼容实现。

¥A browser-compatible implementation of the fetch() function.

FormData 类#>

¥Class FormData

<FormData> 的浏览器兼容实现。

¥A browser-compatible implementation of <FormData>.

global#>

• <Object> 全局命名空间对象。

  ¥<Object> The global namespace object.

在浏览器中，顶层的作用域是全局作用域。这意味着在浏览器中，var something 将定义新的全局变量。在 Node.js 中这是不同的。顶层作用域不是全局作用域；Node.js 模块内的 var something 将是该模块的本地。

¥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.

Headers 类#>

¥Class Headers

<Headers> 的浏览器兼容实现。

¥A browser-compatible implementation of <Headers>.

MessageChannel#>

MessageChannel 类。有关详细信息，请参阅 MessageChannel。

¥The MessageChannel class. See MessageChannel for more details.

MessageEvent#>

MessageEvent 类。有关详细信息，请参阅 MessageEvent。

¥The MessageEvent class. See MessageEvent for more details.

MessagePort#>

MessagePort 类。有关详细信息，请参阅 MessagePort。

¥The MessagePort class. See MessagePort for more details.

module#>

此变量可能看起来是全局的，但实际上不是。参见 module。

¥This variable may appear to be global but is not. See module.

performance#>

perf_hooks.performance 对象。

¥The perf_hooks.performance object.

process#>

• <Object>

进程对象。参阅 process 对象 章节。

¥The process object. See the process object section.

queueMicrotask(callback)#>

• callback <Function> 要排队的函数。

  ¥callback <Function> Function to be queued.

queueMicrotask() 方法将微任务排队以调用 callback。如果 callback 抛出异常，将触发 process 对象 'uncaughtException' 事件。

¥The queueMicrotask() method queues a microtask to invoke callback. If callback throws an exception, the process object 'uncaughtException' event will be emitted.

微任务队列由 V8 管理，并且可以以类似于 process.nextTick() 队列的方式使用，后者由 Node.js 管理。在 Node.js 事件循环的每次轮询中，process.nextTick() 队列总是在微任务队列之前处理。

¥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.

// 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(key);
  if (hit !== undefined) {
    queueMicrotask(() => {
      this.emit('load', hit);
    });
    return;
  }

  const data = await fetchData(key);
  this._cache.set(key, data);
  this.emit('load', data);
}; 拷贝

require()#>

此变量可能看起来是全局的，但实际上不是。参见 require()。

¥This variable may appear to be global but is not. See require().

Response#>

<Response> 的浏览器兼容实现。

¥A browser-compatible implementation of <Response>.

Request#>

<Request> 的浏览器兼容实现。

¥A browser-compatible implementation of <Request>.

setImmediate(callback[, ...args])#>

setImmediate 在 定时器 部分中描述。

¥setImmediate is described in the timers section.

setInterval(callback, delay[, ...args])#>

setInterval 在 定时器 部分中描述。

¥setInterval is described in the timers section.

setTimeout(callback, delay[, ...args])#>

setTimeout 在 定时器 部分中描述。

¥setTimeout is described in the timers section.

SubtleCrypto#>

<SubtleCrypto> 的浏览器兼容实现。只有在编译 Node.js 二进制文件时包含对 node:crypto 模块的支持，此全局才可用。

¥A browser-compatible implementation of <SubtleCrypto>. This global is available only if the Node.js binary was compiled with including support for the node:crypto module.

TextDecoder#>

WHATWG TextDecoder 类。参阅 TextDecoder 章节。

¥The WHATWG TextDecoder class. See the TextDecoder section.

TextEncoder#>

WHATWG TextEncoder 类。参阅 TextEncoder 章节。

¥The WHATWG TextEncoder class. See the TextEncoder section.

URL#>

WHATWG URL 类。参阅 URL 章节。

¥The WHATWG URL class. See the URL section.

URLSearchParams#>

WHATWG URLSearchParams 类。参阅 URLSearchParams 章节。

¥The WHATWG URLSearchParams class. See the URLSearchParams section.

WebAssembly#>

• <Object>

充当所有 W3C WebAssembly 相关功能的名称空间的对象。有关用法和兼容性，请参阅 Mozilla 开发者网络。

¥The object that acts as the namespace for all W3C WebAssembly related functionality. See the Mozilla Developer Network for usage and compatibility.