【学习笔记】ES6 标准 - Promise、generator

const fs = require('fs');

const readFile = function (fileName) {
    return new Promise((resovlve, reject)=>{
        fs.readFile(fileName,(err,data)=>{
            if(err) reject(err);
            resovlve(data)
        })
    })
}

//Promise
readFile('./modules/a.text').then(res=>{
    console.log(res.toString());
    return readFile('./modules/b.text')
}).then(res=>{
    console.log(res.toString())
});

//generator
function * gen() {
    yield readFile('./modules/a.text');
    yield readFile('./modules/b.text');
}
let g1 = gen();
g1.next().value.then(res=>{
    console.log(res.toString())
    return g1.next().value;
}).then(res=>{
    console.log(res.toString())
})

//async
async function fn() {
    let [a,b] = await Promise.all([
        readFile('./modules/a.text'),
        readFile('./modules/b.text')
    ]);
    console.log(a.toString())
    console.log(b.toString())

    /*let f1,f2;
    try{
        f1 = await ;
        f2 = await readFile('./modules/b.text');
    }catch (e) {
        console.log('错误')
    }
    console.log(f1.toString());
    console.log(f2.toString());*/
}
fn();