async和await 使用--- theme: geek-black highlight: a11y-dark ---

await后面接一个会return new promise的函数并执行它

await只能放在async函数里

function fn1(){
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve(5)
        }, 1000);
    })
}

function fn2(data){
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve(data * 100)
        }, 2000);
    })
}

async function req(){
    //同步方式执行异步
    const data1 = fn1()   //等待1秒后返回数据再往下执行
    const data2 = fn2(data1)   //拿data1 去请求2秒后, 往下走
    console.log(new Date(), data2)   //总共3秒后  输出500
}
req()