function onloadEvent(func){
 var one=window.onload
 if(typeof window.onload!='function'){
  window.onload=func
 }
 else{
  window.onload=function(){
   one();
   func();
  }
 }
}
function showtable(){
 var tableid='table';  //表格的id
 var overcolor='#d6ecf2'; //鼠标经过颜色
 var color3='#fff';  //第一种颜色
 var color4='#fcfcd6';  //第二种颜色
 var tablename=document.getElementById(tableid)
 var tr=tablename.getElementsByTagName("tr")
 for(var i=1 ;i<tr.length;i++){
  tr[i].onmouseover=function(){
   this.style.backgroundColor=overcolor;
  }
  tr[i].onmouseout=function(){
   if(this.rowIndex%2==0){
    this.style.backgroundColor=color3;
   }else{
    this.style.backgroundColor=color4;
   }
  }
  if(i%2==0){
   tr[i].className="color3";
  }else{
   tr[i].className="color4";
  }
 }
}
onloadEvent(showtable);