NicetomEetU_:

async/await 本质是 Promise 的语法糖

[code=javascript]

async function async1(){

console.log('async1 start')

await async2();

console.log('async1 end')

}

async function async2(){

await console.log('async2 start');

return new Promise(res => {

setTimeout(() => {

console.log("async2 end");

res();

}, 2000);

})

}

async1()

[/code]

这段代码改写成 Promise 链式调用对放入微队列的时机就比较好理解了

[code=javascript]

function async1() {

console.log('async1 start');

return async2().then(() => {

console.log('async1 end');

});

}

function async2() {

console.log('async2 start');

return new Promise(res => {

setTimeout(() => {

console.log('async2 end');

res();

}, 2000);

});

}

async1();

[/code]