寫出下面代碼執(zhí)行之后的結(jié)果，并分析原理

async function async1(){
    console.log('async1 start')
    await async2();
    console.log('async1 end');
}
async function async2(){
    console.log('async2');
}
console.log('script start');
setTimeout(function(){
    console.log('setTimeout');
},0);
async1();
new Promise(function(resolve){
    console.log('promise1');
    resolve();
}).then(function(){
    console.log('promise2');
});
console.log('script end');

執(zhí)行結(jié)果：

script start
async1 start
async2
promise1
script end
async1 end
promise2
setTimeout

分析：

image.png

for (var i=0;i<5;i++){
    ~function(j){
        setTimeout(function(){
            console.log(j)
        },100)
    }(i)
}

執(zhí)行結(jié)果：

0
1
2
3
4

分析：
~自執(zhí)行函數(shù)
利用閉包的特性，將參數(shù)鎖定