const fs=require("fs")
let p=new Promise((resolve, reject)=>{
    fs.readFile('./resource/1.html',(err,data)=>{
        if(err) reject(err);
        resolve(data)
    })
})
let p2=p.then(value => {
    return new Promise((resolve, reject)=>{
        fs.readFile('./resource/2.html',(err,data)=>{
            if(err) reject(err);
            resolve([value,data])
        })
    })
},reason => {

});
let p3=p2.then(value => {
    return new Promise((resolve, reject)=>{
        fs.readFile('./resource/4.html',(err,data)=>{
            if(err) reject(err);
            value.push(data)
            resolve(value)
        })
    })
},reason => {
})
p3.then(value => {
    console.log(value.join(''))
})