Javascript 异步/等待程序顺序

Question

const function1 = () => 
      new Promise(function(resolve,reject) {
          setTimeout(() => {
             resolve(10)
          },6000)
       });
       
const function2 = async () => {
    console.log("first");

    const val = await function1()
    console.log("second");
    return val
}

console.log("third -- " ,function2())

我期望消息的顺序如下:

first
second
third -- Promise { <pending> }>

但结果给出了以下输出:

first 
third -- Promise { <pending> }
second

谁能帮我理解这一点吗？

Answer 1

您需要await，而不是调用function2()

    await function2(); // logs first (6 seconds expire) second, 10

这是因为你需要等待函数 2 解析 Promise 才能继续

您可以执行以下操作以获得所需的结果

    const function3 = async () => {
        const third = await function2();
        console.log( "third --", third ) 
    }
    function3();