generator promise async 读取文件

const fs = require('fs')

const readFile = (path, options) => {
    return new Promise((resolve, reject) => {
        fs.readFile(path, options, (err, data) => {
            if (err) throw err
            resolve(data)
        })
    })
}

readFile('data/a.txt', 'utf-8').then(res => {
    console.log(res) 
    return readFile('data/a.1.txt', 'utf-8')
}).then(res => {
    console.log(res) 
    return readFile('data/a.2.txt', 'utf-8')
}).then(res => {
    console.log(res) 
})

function * gen (){
    yield readFile('data/a.txt', 'utf-8')
    yield readFile('data/a.1.txt', 'utf-8')
    yield readFile('data/a.2.txt', 'utf-8')
}

let g1 = gen()

g1.next().value.then(res => {
    console.log(res)
    return g1.next().value
}).then(res => {
    console.log(res)
    return g1.next().value
}).then(res => {
    console.log(res)
})

async function async1() {
    try{
        let f1 = await readFile('data/a.txt', 'utf-8')
        let f2 = await readFile('data/a.1.txt', 'utf-8')
        let f3 = await readFile('data/a.2.txt', 'utf-8')
        console.log(f1)
        console.log(f2)
        console.log(f3)   
    }catch(e) {
        console.log(e)
    }
}
async1()

data目录下的a.txt  随便定义内容