一个跑马灯的几种设计思路

小学选手~

先看效果 ：http://sandbox.runjs.cn/show/994ghu9f

<ul id="traffic" class="wait">
  <li><span></span></li>
  <li><span></span></li>
  <li><span></span></li>
</ul>


#traffic > li{
  display: block;
}
 
#traffic span{
  display: inline-block;
   50px;
  height: 50px;
  background-color: gray;
  margin: 5px;
  border-radius: 50%;
}
 
#traffic.stop li:nth-child(1) span{
  background-color: #a00;
}
 
#traffic.wait li:nth-child(2) span{
  background-color: #aa0;
}
 
#traffic.pass li:nth-child(3) span{
  background-color: #0a0;
}

const traffic = document.getElementById("traffic");
 
(function reset(){
  traffic.className = "wait";
 
  setTimeout(function(){
      traffic.className = "stop";
      setTimeout(function(){
        traffic.className = "pass";
        setTimeout(reset, 2000)
      }, 2000)
  }, 2000);
})();

2初中水平~（数据抽象

const traffic = document.getElementById("traffic");
 
var stateList = ["wait", "stop", "pass"];
 
var currentStateIndex = 0;
 
setInterval(function(){
  var state = stateList[currentStateIndex];
  traffic.className = state;
  currentStateIndex = (currentStateIndex + 1) % stateList.length;
}, 2000);

2补充--普通青年水平~~

const traffic = document.getElementById("traffic");
 
function start(traffic, stateList){
  var currentStateIndex = 0;
 
  setInterval(function(){
    var state = stateList[currentStateIndex];
    traffic.className = state;
    currentStateIndex = (currentStateIndex + 1) % stateList.length;
  }, 2000);
}
 
start(traffic, ["wait", "stop", "pass"]);

3高中水平~过程抽象

const traffic = document.getElementById("traffic");

function poll(...fnList){
  let stateIndex = 0;
 
  return function(...args){
    let fn = fnList[stateIndex++ % fnList.length];
    return fn.apply(this, args);
  }
}
 
function setState(state){
  traffic.className = state;
}
 
let trafficStatePoll = poll(setState.bind(null, "wait"),
                            setState.bind(null, "stop"),
                            setState.bind(null, "pass"));
 
setInterval(trafficStatePoll, 2000);

4 大学版本~各种新特性哈哈

const traffic = document.getElementById("traffic");
 
function wait(time){
  return new Promise(resolve => setTimeout(resolve, time));
}
 
function setState(state){
  traffic.className = state;
}
 
function reset(){
  Promise.resolve()
    .then(setState.bind(null, "wait"))
    .then(wait.bind(null, 1000))
    .then(setState.bind(null, "stop"))
    .then(wait.bind(null, 2000))
    .then(setState.bind(null, "pass"))
    .then(wait.bind(null, 3000))
    .then(reset);
}
 
reset();

5 宇宙版本……现在有点看不懂 留在以后再看

const trafficEl = document.getElementById("traffic");
 
function TrafficProtocol(el, reset){
  this.subject = el;
  this.autoReset = reset;
  this.stateList = [];
}
 
TrafficProtocol.prototype.putState = function(fn){
  this.stateList.push(fn);
}
 
TrafficProtocol.prototype.reset = function(){
  let subject = this.subject;
 
  this.statePromise = Promise.resolve();
  this.stateList.forEach((stateFn) => {
    this.statePromise = this.statePromise.then(()=>{
      return new Promise(resolve => {
        stateFn(subject, resolve);
      });
    });
  });
  if(this.autoReset){
    this.statePromise.then(this.reset.bind(this));
  }
}
 
TrafficProtocol.prototype.start = function(){
  this.reset();
}
 
var traffic = new TrafficProtocol(trafficEl, true);
 
traffic.putState(function(subject, next){
  subject.className = "wait";
  setTimeout(next, 1000);
});
 
traffic.putState(function(subject, next){
  subject.className = "stop";
  setTimeout(next, 2000);
});
 
traffic.putState(function(subject, next){
  subject.className = "pass";
  setTimeout(next, 3000);
});
 
traffic.start();

参考：http://mp.weixin.qq.com/s?__biz=MzAxODE2MjM1MA==&mid=2651551635&idx=1&sn=a7d6e09a94ef854a94ed578a9de70015&chksm=8025a052b752294443a3a89745ded0cc158bcba1fb6e5af1fa2c223f379341da3b58c8fe00a9&mpshare=1&scene=23&srcid=0108Rg5m1KroA9GpzeTWQBMh#rd

http://www.cnblogs.com/yunfeifei/p/4453690.html