群里发了一份js代码，要求三分钟看懂，看了十分钟都没看懂，有木有。
先记录下。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
#lamp {
width: 100px;
height: 100px;
border-radius: 50px;
}
</style>
</head>
<body>
<div id="lamp"></div>
<script src="jtd.js"></script>
</body>
</html>
//红灯亮三秒，绿灯亮秒 灰灯一秒 依次循环
var lampstyle= document.getElementById("lamp").style;
function setColor(color,time){
return function(callback){
lampstyle.backgroundColor=color;
setTimeout(callback,time);
};
}
var queue = function(funcs) {
(function next() {
if(funcs.length > 0) {
var f = funcs.shift();
f(next);
}
})();
};
var setredcolor=setColor("red",3000);
var setgreencolor=setColor("green",2000);
var setgraycolor= setColor("gray",1000);
+function tick(){
queue([
setredcolor,
setgreencolor,
setgraycolor,
tick]);
}();
