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Copy path闭包缓存.html
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闭包缓存.html
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
</body>
<script>
let log = console.log.bind(console)
let a = function(cacheName, arg1) {
let o = {
// key是参数一传进来的
// 'lin': {
// count: 10,
// }
}
let b = function(arg2) {
log('cacheName ', cacheName)
if (o[cacheName]) {
log('缓存中获取')
// 缓存中获取
return o[cacheName].count + arg2
} else {
log('创建新的')
// 创建新的
let n = arg1 + arg2
// log('arg1 arg2', arg1, arg2)
o[cacheName] = {
count: n,
}
return o[cacheName].count
}
}
// 销毁闭包
let destroy = function() {
log('销毁闭包 ', cacheName)
delete o[cacheName]
}
return {
next: b,
destroy: destroy,
}
}
let test1 = a('lin', 1)
log(test1.next(9)) // 创建一个新的 得到值 10 初始的1+9
log(test1.next(2)) // 拿到缓存 得到值 12 10+2
log(test1.next(3)) // 拿到缓存 得到值 13 10+3
log(test1.next(1)) // 拿到缓存 得到值 11 10+1
test1.destroy() // 销毁闭包
log(test1.next(99)) // 创建一个新的 得到值 100 初始的1+99
log(test1.next(1)) // 拿到缓存 得到值 100 100+1
setTimeout(() => {
log('time')
}, 0);
new Promise((resolve, reject)=> {
log('p1 同步')
resolve()
}).then(()=>{
log('p1 异步')
new Promise((resolve, reject)=> {
log('p2 同步')
resolve()
}).then(()=>{
log('p2 异步')
})
})
</script>
</html>