十一、等待者模式
通过对多个异步进程的监听，对未来事件进行统一管理
代码语言：javascript复制1、等待者模式例子
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<script>
/*
waiter.when(异步事件1, 异步事件2, ...).done(fn).fail(fn)
*/
//等待者模式
// 成熟的等待者模式 有 async/await 模式 和 promise模式
function Waiter() {
var dfd = []; // 用来存放异步事件
var doneArray = []; // 用来存放done注册成功之后的回调
var failArray = []; // 存放失败的回调
this.when = function () {
// 获取arguments -> 一个类数组对象
dfd = Array.prototype.slice.call(arguments); // 将类数组转换成数组
for (var i = dfd.length -1; i >= 0; i--) {
var d = dfd[i];
if (!d || d.rejected || d.resolved || !(d instanceof Defer)) {
dfd.splice(i, 1);
}
}
return this
}
this.done = function () {
var args = Array.prototype.slice.call(arguments);
doneArray = doneArray.concat(args)
return this
}
this.fail = function () {
var args = Array.prototype.slice.call(arguments);
failArray = failArray.concat(args)
return this
}
this.Defered = function () {
return new Defer()
}
var Defer = function () {
this.resolved = false;
this.rejected = false;
}
Defer.prototype = {
resolve: function () {
this.resolved = true;
for (var i = 0; i < dfd.length; i ) {
if (!dfd[i].resolved) {
return
}
}
// 如果全部完成，就不会被return出去，则可执行下面的语句
// 执行成功的回调函数
_exec(doneArray)
},
reject: function () {
this.rejected = true;
// 执行失败的回调
_exec(failArray)
}
}
function _exec(arr) {
for( var i = 0; i < arr.length; i ) {
arr[i] && arr[i]()
}
}
}
var waiter = new Waiter()
var async1 = function () {
var dfd = waiter.Defered()
setTimeout(function () {
console.log('async1 done');
dfd.resolve()
}, 1000)
return dfd
}
var async2 = function () {
var dfd = waiter.Defered()
setTimeout(function () {
console.log('async1 done');
dfd.resolve()
}, 2000)
return dfd
}
waiter.when(async1(), async2()).done(function () {
console.log('success');
}).fail(function () {
console.log('fail');
})
</script>
</head>
<body>
</body>
</html>
