node内置模块

（1）events

1. 触发自定义事件

类似jq的trigger函数，用emit去触发另一个事件

const RootEvent = require('events');

class CurEvent extends RootEvent{

}

const DemoEvent = new CurEvent();

DemoEvent.on('printme',function(){
    console.log('------------------------------------');
    console.log('i am the best');
    console.log('------------------------------------');
});

setInterval(()=>{
    DemoEvent.emit('printme');
},1000)

（2）fs

1. 创建流读取txt文件

//向txt文件中写入数据，监听finish事件来结束写入
const fs = require('fs');

const ws = fs.createWriteStream('./article.txt');

const continuewrite = setInterval((err)=>{
    if(err) throw err;
    const num = parseInt(Math.random()*10);
    console.log('------------------------------------');
    console.log(num);
    console.log('------------------------------------');
    if(num < 9){
        ws.write(num + '');
    }else{
        clearInterval(continuewrite);
        ws.end();
    }
    
},1000);

ws.on('finish',()=>{
    console.log('done');
})