Understanding and analyzing nodejs event monitoring and triggering_node.js

This article analyzes the monitoring and triggering of nodejs events through examples. Share it with everyone for your reference. The specific analysis is as follows:

Regarding the event driver of nodejs, I still didn’t understand it after reading "nodejs in a simple way" (maybe the writing is a bit deep, or my understanding is not good enough). Today I saw an article on the monitoring and triggering of nodejs events in the Turing community , because the examples given are easy to understand for many people, so I also have a general understanding of nodejs event driving.

The following content refers to the Turing community article (Address: http://www.ituring.com.cn/article/177478)

First, let’s learn about the Event module of nodejs:

Most modules in Node.js inherit from the Event module. The Event module (events.EventEmitter) is a simple implementation class of the event listener pattern. Its object has methods to implement basic event listening modes such as addListener, on, once, removeListener, removeAllListeners, and emit.

First look at an example:

var events = require("events");
var emitter = new events.EventEmitter();//创建了事件监听器的一个对象
// 监听事件some_event
emitter.on("some_event", function(){
  console.log("事件触发，调用此回调函数");
});
setTimeout(function(){
  emitter.emit("some_event");   //触发事件some_event
},3000);

Seeing this example reminds me of jQuery’s custom events:

//给element绑定hello事件
element.on("hello",function(){
  alert("hello world!");
});
//触发hello事件
element.trigger("hello");

With this comparison, it is easy to understand the monitoring and triggering of nodejs events. emit is equivalent to the trigger trigger event in jQuery.

I hope this article will be helpful to everyone’s nodejs programming.