使用Javascript监控前端相关数据的代码

function error(msg,url,line){
  var REPORT_URL = "xxxx/cgi"; // 收集上报数据的信息
  var m =[msg, url, line, navigator.userAgent, +new Date];// 收集错误信息，发生错误的脚本文件网络地址，用户代理信息，时间
  var url = REPORT_URL + m.join('||');// 组装错误上报信息内容URL
  var img = new Image;
  img.onload = img.onerror = function(){
   img = null;
  };
  img.src = url;// 发送数据到后台cgi
}
// 监听错误上报
window.onerror = function(msg,url,line){
  error(msg,url,line);
}

function _performance(){
  var REPORT_URL = "xxxx/cgi?perf=";
  var perf = (window.webkitPerformance ? window.webkitPerformance : window.msPerformance ),
   points = ['navigationStart','unloadEventStart','unloadEventEnd','redirectStart','redirectEnd','fetchStart','domainLookupStart','connectStart','requestStart','responseStart','responseEnd','domLoading','domInteractive','domContentLoadedEventEnd','domComplete','loadEventStart','loadEventEnd'];
  var timing = pref.timing;
  perf = perf ? perf : window.performance;
  if( perf && timing ) {
   var arr = [];
   var navigationStart = timing[points[0]];
   for(var i=0,l=points.length;i<l;i++){
     arr[i] = timing[points[i]] - navigationStart;
   }
  var url = REPORT_URL + arr.join("-");
  var img = new Image;
  img.onload = img.onerror = function(){
   img=null;
  }
  img.src = url;
}

<script>var cssLoadStart = +new Date</script>
<link rel="stylesheet" href="xxx.css" type="text/css" media="all">
<link rel="stylesheet" href="xxx1.css" type="text/css" media="all">
<link rel="stylesheet" href="xxx2.css" type="text/css" media="all">
<sript>
  var cssLoadTime = (+new Date) - cssLoadStart;
  var jsLoadStart = +new Date;
</script>
<script type="text/javascript" src="xx1.js"></script>
<script type="text/javascript" src="xx2.js"></script>
<script type="text/javascript" src="xx3.js"></script>
<script>
  var jsLoadTime = (+new Date) - jsLoadStart;
  var REPORT_URL = 'xxx/cgi?data='
  var img = new Image;
  img.onload = img.onerror = function(){
   img = null;
  };
  img.src = REPORT_URL + cssLoadTime + '-' + jsLoadTime;
</script>