Question

问题显示我正在一个接一个地使用2个异步函数。他们每个人都从智能合约中调用该方法，并在“回执”回调中执行其他工作。

代码是：

await first()
await second()

let first = async function () {
   await myContract.methods.methodOne()
   .send({from: account})
   .on('receipt', async () => {
    console.log('1')
    async someAsyncFunction()
   })
}

let second = async function () {
   await myContract.methods.methodOne()
   .send({from: account})
   .on('receipt', async () => {
    console.log('2')
    console.log(variableFromContract) // undefined
   })
}

let someAsyncFunction = async function () {
   setTimeout(() => {
      variableFromContract = 10;
   }, 2000);
}

someAsyncFunction有什么问题？
为什么它在second（）函数之前没有运行？

先谢谢了。（我使用的是web3.js 1.0.0-beta.37版本）

Answer 1

经过多次尝试，我找到了答案，不需要在'receipt'回调中放入异步方法，只需使用

...
.on('receipt', () => {
    console.log('block mined') 
})
.then( async () => { 
    await someAsyncFunction() // put the code here
})

Answer 2

这里有几个问题：

let first = async function () {
   await myContract.methods.methodOne()
   .send({from: account})
   .on('receipt', async () => {
    console.log('1')
    async someAsyncFunction() // <--- should be return await someAsyncFunction() so you have a value to pass onto second
   })
}

let second = async function () {
   await myContract.methods.methodOne()
   .send({from: account})
   .on('receipt', async () => { // <-- this is an async function but you don't await anything inside of it
    console.log('2')
    console.log(variableFromContract) // undefined
   })
}

let someAsyncFunction = async function () { // again async function but awaiting nothing to resolve.
   setTimeout(() => {
      variableFromContract = 10;
   }, 2000);
}

web3.js回调中的异步/等待订单问题

2 个答案: