1、回调函数方式

doFirstThing((err, data) => {if (err) {console.log(err);return;}doSecondThing(data, function(err, data){if (err) {console.log(err);return;}doThirdThing(data, function(err, data){if (err) {console.log(err);return;}})})
})

2、Promise 方式

function takeLongTime(n) {return new Promise(resolve => {setTimeout(() => {resolve(n + 200)},)})}
function doThing (n) {return takeLongTime(n);
}
const time1 = 200;
doThing(time1)
.then(time2 => doThing(time2))
.then(time3 => doThing(time3))
.catch(err => {console.log(err)
})
复制代码

上面的代码每次异步调用递进200ms，并把下次需要延迟的时间传给下个异步函数

3、async & await

async function doThings () {try {const data1 =  await doThing(200);const data2 = await doThing(data1);const data3 = await doThing(data2);} catch (err => {console.log(err)}) }