宏任务-微任务-面试题

面试题一

/*
promise1
2
then1
queueMicrotask1
then3
setTimeout1
then2
then4
setTimeout2
*/
console.log("script start")//主任务1
setTimeout(function () {
console.log("setTimeout1");//宏任务1
new Promise(function (resolve) {
resolve();
}).then(function () {//宏任务1:微任务1
new Promise(function (resolve) {
resolve();
}).then(function () {//宏任务1:微任务2
console.log("then4");//宏任务1:微任务2:console.log
});
console.log("then2");//宏任务1:微任务1:console.log
});
});

new Promise(function (resolve) {
console.log("promise1");//主任务2
resolve();
}).then(function () {
console.log("then1");//微任务1:console.log
});

setTimeout(function () {
console.log("setTimeout2");//宏任务2
});

console.log(2);//主任务3

queueMicrotask(() => {
console.log("queueMicrotask1")//微任务2
});

new Promise(function (resolve) {
resolve();
}).then(function () {//微任务3
console.log("then3");
});
console.log("script end")//主任务4

面试题二

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')

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