Promise是ES6中新增的构造函数
Promise表示一个异步操作的最终状态（完成或失败），以及其返回的值。
——————————直接上代码————————————
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
body{
background-color: #ccc;
}
div{
width: 100px;
height: 100px;
border: 1px solid black;
border-radius: 50%;
}
#redLight{
color: black;
text-align: center;
font-size: 35px;
line-height: 100px;
}
#greenLight{
color: black;
text-align: center;
font-size: 35px;
line-height: 100px;
}
#yellowLight{
color: black;
text-align: center;
font-size: 35px;
line-height: 100px;
}
</style>
</head>
<body>
<div id="redLight">3</div>
<div id="greenLight"></div>
<div id="yellowLight"></div>
</body>
</html>
<script type="text/javascript" src="js/packageFunction.js"></script>
<script type="text/javascript">
// 创建三个灯的对象
function red(){
// 定时
let count = 3;
$("redLight").innerHTML=count;
$("redLight").style.backgroundColor = "red";
return new Promise(function(resolve,reject){
// 每一个灯创建一个定时器
let timer = setInterval(function(){
// 灯的颜色改变
$("redLight").style.backgroundColor = "red";
count--;
$("redLight").innerHTML = count;
if(count<=0){
count=0;
clearInterval(timer);
$("redLight").style.backgroundColor = "#ccc";
$("redLight").innerHTML="";
resolve();
}
},1000)
});
}
function green(){
let count = 3;
$("greenLight").innerHTML=count;
$("greenLight").style.backgroundColor = "green";
return new Promise(function(resolve,reject){
let timer = setInterval(function(){
count--;
$("greenLight").innerHTML = count;
if(count<=0){
count=0;
clearInterval(timer);
$("greenLight").style.backgroundColor = "#ccc";
$("greenLight").innerHTML="";
resolve();
}
},1000)
});
}
function yellow(){
let count = 3;
$("yellowLight").innerHTML=count;
$("yellowLight").style.backgroundColor = "yellow";
let n = new Promise(function(resolve,reject){
let timer = setInterval(function(){
count--;
$("yellowLight").innerHTML = count;
if(count<=0){
count=0;
clearInterval(timer);
$("yellowLight").style.backgroundColor = "#ccc";
$("yellowLight").innerHTML="";
resolve();
}
},1000)
});
return n;
}
function shine(){
// ES6新写法，避免了构造地狱
red().then(green).then(yellow).then(shine);
}
window.onload = function(){
shine();
}
</script>
小弟欢迎大家进行各种批评、指导。
没有封装过程看的更加的直白。