Promise.all 使用方法

Promise.all([fn(),fn()]) 都返回resolve(); 才能够拿到成功的返回值
Promise.all([fn(),fn()]) 有一个返回reject(), 则进入catch(error), 拿到失败的返回值

1.await 可以获得多个promise 的返回结果

2. Promise.all 返回的也是promise，所以可以直接await Promise.all();

1. 使用Promise

function fn(){
    return new Promise((resolve,reject)=>{
        let randomNum = parseInt(Math.random()*6+1);
        console.log(randomNum);
        if(randomNum>3){
            resolve('买'); 
        }
        else{
            reject('不买');
        }
    })
}
 
Promise.all([fn(),fn()]).then((x)=>{console.log(x,'success')},(y)=>{console.log(y,'error');});

使用await

await 是可以获得多个promise 返回结果的，Promise.all()返回的也是promise结果。所以想要使用await 拿到多个promise的返回值，可以直接await Promise.all();

function fn(){
    return new Promise((resolve,reject)=>{
        let randomNum = parseInt(Math.random()*6+1);
        console.log(randomNum);
        if(randomNum>3){
            resolve('买'); 
        }
        else{
            reject('不买');
        }
    })
}
async function test(){
    try{
    let res = await Promise.all([fn(),fn()]);
    console.log(res,'success');
    }
    catch(error){
        console.log(error,'error');
    }
}
 
test();

await Promise.all(arr.map((item) => geo.getLocation(item.lon, item.lat).then(address => item.address = address)));

let res = await Promise.all([
        checkIDNumber(this.driverObj.driverId, IDNumber),
        certificate(this.driverObj.driverId, this.driverObj.certificate)]);
      res.forEach(p => p&&!p.flag && p.msg && this.$message.error(p.msg))
      return res.every(p => p ? p.flag : 1);
    },

return Promise.all(allPromise)
    .then(arr => arr.flat())
    .catch(() => []);
}

Promise.all(query).then(() => {
            this.animationDuration = `${this.textWidth / this.speed}s`
            this.animationDelay = `-${this.boxWidth / this.speed}s`
            setTimeout(() => {
              this.animationPlayState = 'running'
            }, 1000)
          })

switch (type) {
        case 'left':
          Promise.all([
            this.move(this.selector, leftWidth),
            this.move(this.leftButton, 0),
            this.move(this.rightButton, rightWidth * 2)
          ]).then(() => {
            this.setEmit(leftWidth, type)
          })
          break
        case 'right':
          Promise.all([
            this.move(this.selector, -rightWidth),
            this.move(this.leftButton, -leftWidth * 2),
            this.move(this.rightButton, 0)
          ]).then(() => {
            this.setEmit(-rightWidth, type)
          })
          break
        default:
          Promise.all([
            this.move(this.selector, 0),
            this.move(this.leftButton, -leftWidth),
            this.move(this.rightButton, rightWidth)
          ]).then(() => {
            this.setEmit(0, type)
          })

      }