async、await

1, async function returns a target Promise

2, await is asynchronous wait, should be followed by a Promise objects Promise objects if not, it will be turned into an immediate resolve of Promise

3, await a waiting Promise is an object, the value of resolve Promise state will return the object, instead of returning the object Promise

 

onLoad: async function (options) {
    const aa = await this.promise1()   //没有await
    console.log(aa)
  },

  promise1(){
    return new Promise((resolve, reject) => {
      resolve('aaaa')
    })
  },

Promise output target

Promise {<resolved>: "aaaa"}

 

onLoad: async function (options) {
    const aa =  await this.promise1()   //有await
    console.log(aa)
  },

  promise1(){
    return new Promise((resolve, reject) => {
      resolve('aaaa')
    })
  },

Promise resolve the target value of the output

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