事件发射器和节点事件目标之间的差异
原文:https://www . geesforgeks . org/difference-event emitter-and-nodeventtarget/
事件发射器:所有事件发射器在添加新侦听器时发出事件“新侦听器”，在移除现有侦听器时发出事件“移除侦听器”。它由事件模块定义和公开:
要导入事件发射器，请使用以下导入语句:
const EventEmitter = require('events');
节点事件目标:事件目标和事件对象是事件目标网络应用编程接口的特定于节点. js 的实现，由一些节点. js 核心应用编程接口公开。
区别T5【事件发射器】T8T11【节点事件目标】:
| Event transmitter | Node event target |
|---|---|
| It is inherited from the event module of JavaScript. | Is a modified subset of the event emitter API and inherits from this API. |
| It realizes the relationship between IS-A and Event modules. | It realizes the IS-A relationship between and event target API. |
| In Event Emitter , we can register multiple listeners for the same event. | Each event type can register any listener once. If you try to register a listener several times, it will be ignored. |
| It imitates most from events such as , [error], [class], [emission] and . | 它没有模仿完整的事件发射器 API，如前置监听者()、前置监听者()、监听者()等。 |
| The default behavior is to record with information and end the current execution. | For events of type " error ", it does not implement any default behavior. |
| If an error occurs in the event transmitter instance, the typical operation is to issue an "error" event. | The event listener object is supported as a handler for all event types. |
| All event emitters emit the event " new listener " when adding a new listener, and the event "removeListener" when removing the listener. | It is not an instance of the event transmitter , and in most cases, it cannot be used instead of the event transmitter. |
| 语法: |
emitter.once(
eventName, listener)
| 语法:
nodeEventTarget.once(
type, listener[, options])
|
参考:https://nodejs . org/API/events . html # events _ nodeventtarget _ vs _ event emitter
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