zjtd面试题

async function async1() {
    console.log('async 1 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'); //--------

1. await和then是微任务，要在主线程结束后再执行

2. settimeout是宏任务，要在微任务结束后再执行

微任务：promise async await

宏任务：定时器 事件绑定