前置知识
- Promise
- 事件循环
- 定时器
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<style>
.box {
width: 100px;
height: 100px;
background-color: red;
color: blue;
transition: all 1s;
line-height: 100px;
text-align: center;
cursor: pointer;
user-select: none;
}
.box:hover {
background-color: blue;
color: red;
transform: scale(.5);
}
</style>
</head>
<body>
<div class="box">点击</div>
<script>
(async function (win) {
function task() {
return new Promise((resolve, reject) => {
win.request = resolve
win.rej = reject
})
}
var events = new Map()
async function eventLoop() {
while (true) {
const { api: key, params } = await task();
if (events.has(key)) { // 精准触发
events.get(key)(params)
}
}
}
win.addEvent = function (event) {
events.set(event.key, event.event)
}
function testEvent(params) {
console.log('请求此api次数为：' + params.count)
}
addEvent({ key: '/getUser', event: testEvent }) // 模拟服务端订阅了此事件
eventLoop()
})(window)
const btn = document.querySelector('.box');
let i = 0
btn.addEventListener('click', () => {
i++
request({ api: '/getUser', params: { token: '123456', count: i } }) // 相当于发起api请求
})
// 模拟循环发起请求
// for (let index = 0; index < 100000; index++) {
// setTimeout(() => { // 如果不走定时器异步则会导致只有一个微任务被添加到队列,因为当次Promise已结束
// request({ api: '/getUser', params: { token: '123456', count: index } }) // 相当于发起api请求
// }, 0);
// }
</script>
</body>
</html>
