javascript yiel代码：

 

function delay(time) {

    return new Promise(function (resolve, reject) {

        setTimeout(() => {

            resolve();

        }, time);

    });

}

 

function* output() {

    yield delay(500).then(() => console.log(1));

    yield (function () { console.log(2); return 'aa' })()

    yield delay(200).then(() => console.log(3));

    yield (function () { console.log(4); return 'aa' })()

}

 

function runGen(gen, next) {

    const item = gen.next();

    if (item.done) return;

 

    const { value } = item

    if (value instanceof Promise) {

        value.then(() => runGen(gen))

    } else {

        runGen(gen)

    }

}

 

runGen(output());