Javascript实现网络监测的方法

(function(){
var network = function(){
 var monitor = this;
 /**
  * @param {Funcation} speedInterval
  */
 var speedInterval = null;
 /**
  * @param {Function} networkInterval
  */
 var networkInterval = null;
 /**
  * @param {Function} reNetworkInterval
  */
 var reNetworkInterval = null;
 var time = 5000;
 /**
  * 获取网络连接状态
  */
 var getConnectState = function(){
  return navigator.onLine "网速中断");
  window.clearInterval(reNetworkInterval);
  reNetworkInterval = null;
  endSpeed();
  endNetwork();
  window.setTimeout(function(){
   reNetworkInterval = window.setInterval(function(){
    if (getConnectState() == 1) {
     window.clearInterval(reNetworkInterval);
     reNetworkInterval = null;
     startSpeed();
     startNetwork();
    } else {
     window.clearInterval(reNetworkInterval);
     reNetworkInterval = null;
     disconnect();
    }
   }, time);
  }, 2 * time);
 };
 /**
  * 网络速度
  */
 var speed = {
   /**
    * 网速过慢
    */
   bad : function(){
    // TODO ... 
    console.log("网速过慢");
    window.setTimeout(function(){
     if(getConnectState() == 1) {
      window.clearInterval(networkInterval);
      networkInterval = null;
      startSpeed();
     } else {
      disconnect();
     }
    }, 2 * time);
   },
   /**
    * 网速中等
    */
   medium : function(){
    // TODO ... 
    console.log("网速中等");
   },
   /**
    * 网速极佳
    */
   great : function(){
    // TODO ... 
    console.log("网速极佳");
   }
 };
 /**
  * 开启速度监测
  * @private
  */
 var startSpeed = function(){
  window.clearInterval(speedInterval);
  speedInterval = null;
  if(getConnectState() == 1) {
   speedInterval = window.setInterval(function(){
    var start = new Date().getTime();
    if (getConnectState() == 1) {
     var img = document.getElementById("networkSpeedImage");
     if (!!!img) {
      img = document.createElement("IMG");
      img.id = "networkSpeedImage";
      img.style.display = "none";
      document.body.appendChild(img);
     }
     try {
      img.src = "http://www.baidu.com/img/baidu_jgylogo3.gif" + new Date().getTime();
      img.onload = function(){
       var end = new Date().getTime();
       var delta = end - start;
       if (delta > 200) {
        speed.bad();
       } else if (delta > 100) {
        speed.medium();
       } else {
        speed.great();
       }
      };
     } catch(e){
      speed.bad();
     }
    } else {
     // TODO 网络断开
     disconnect();
    }
   }, time);
  }else {
   // TODO 网络断开
   disconnect();
  }
 };
 /**
  * 停止速度监测
  * @private
  */
 var endSpeed = function(){
  window.clearInterval(speedInterval);
  speedInterval = null;
 };
 /**
  * 开启网络连接监测
  * @private
  */
 var startNetwork = function(){
  if (getConnectState() == 1) {
   networkInterval = window.setInterval(function(){
    if (getConnectState() == 0) {
     disconnect();
    }
   }, time);
  } else{
   disconnect();
  }
 };
 /**
  * 结束网络连接监测
  * @private 
  */
 var endNetwork = function(){
  window.clearInterval(networkInterval);
  networkInterval = null;
 };
 /**
  * 网络监控开始
  */
 this.start = function(){
  startNetwork();
  startSpeed();
 };
 /**
  * 停止网络监控
  */
 this.stop = function(){
  endSpeed();
  endNetwork();
 };
};
  window.network = new network();
}).call(this);
// 调用的时候,直接调用network.start();