async await Promise多个异步代码互相调用示例

  function a1() {
        return new Promise(o => {
            console.log("a1")
            o('a1_1')
        })
    }
    async function a2() {
        const _a2 = await a1()
        console.log(_a2);
        console.log('a2_1');
    }
    function noAsynca3() {
        console.log('noAsync start')
        a2()
        console.log("noAsync end")
    }

  noAsynca3()

　　代码结果一看就知道不符合我们想要是执行顺序

修改代码

  function a1() {
        return new Promise(o => {
            console.log("a1")
            o('a1_1')
        })
    }
    async function a2() {
        const _a2 = await a1()
        console.log(_a2);
        console.log('a2_1');
    }
    async function Asynca3() {
        console.log('start')
        await a2()
        console.log("end")
    }
Asynca3()

代码结果