es7 async / await 简单示例

[WangShuXian6]

es7 async / await

function asyncF(name) {
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve('my name is ' + name)
}, 1000)
})
}

function sum(a, b) { return new Promise((resolve, reject) => { setTimeout(() => { resolve(a + b) }, 1000) }) }

async function fn() { const line = await asyncF('tom') const n = await sum(2, 3) console.log(line + ':' + n) } //2秒后终端显示 //my name is tom:5

[WangShuXian6]

错误处理

test() {
      return new Promise((reslove, reject) => {
        if(true){
          reject('wrong')
        }else{
          reslove('right')
        }
      })
    }

async asyncBegin() {
      let num = await this.test().catch((error)=>{
        console.log(error)
      })
      console.log('num', num)
    }

//wrong
//num undefined

[WangShuXian6]

串行执行异步

test1() async test1(){ await this.test2() await this.test3()

}

async test2(){
  let code=await this.test4()
  console.log(code)
}

async test3(){
  let code=await this.test5()
  console.log(code)
}

test4(){
  return new Promise((resolove,reject)=>{
    setTimeout(()=>{
      resolove(3000)
    },3000)
  })
}

test5(){
  return new Promise((resolove,reject)=>{
    setTimeout(()=>{
      resolove(2000)
    },2000)
  })
}

// 3000 // 2000