The use of async (asynchronous) and await

正确使用方法：

<script>
    let a = []
    async function fun(){
    
        console.log('开始喽！');
        await interface()
        console.log(a,'9999');
    }

    function interface() {
    
        return new Promise((resolve, reject)=>{
    
            setTimeout(()=>{
    
                a = [1,9,22,6]
                console.log('The interface data has been obtained！');
                resolve()
            },2000)
        })
    }
    fun();
</script>

结果：

正常情况下,代码是同步执行的;例如,在函数A的内部调用函数B,Wait for the inner functionB执行完成后,才会执行函数Ain functionB后面的代码.

<script>
    let a = []
    function fun(){
    
        console.log('开始喽！');
        interface()
        console.log(a,'9999');
    }

    function interface() {
    
        for(let i=0; i<10;i++) {
    
            console.log(i);
        }
        a = [1,9,22,6]
    }
    fun();
</script>

结果：

But when the functioninterfaceWhen the interface needs to be adjusted（我是用setTimeoutAnalog tuning interface）,此时函数funThe code in is not executed synchronously,而是异步了

<script>
    let a = []
    function fun(){
    
        console.log('开始喽！');
        interface()
        console.log(a,'9999');
    }

    function interface() {
    
        setTimeout(()=>{
    
            a = [1,9,22,6]
            console.log('The interface data has been obtained！');
        },2000)
    }
    fun();
</script>

结果：