function addLoadEvent(func) {
  var oldonload = window.onload;
  if (typeof window.onload != 'function') {
    window.onload = func;
  } else {
    window.onload = function() {
      oldonload();
      func();
    }
  }
}
addLoadEvent(changsho1);
addLoadEvent(changsho2);
function changsho1(){
		var a=document.getElementById("comp1").getElementsByTagName("li");
		var b=false;
			for(var j=0;j<a.length;j++){
				if(b==true){
					a[j].className="changecolor";
					b=false;
					}
					else{
					b=true;
					}//隔行换色效果
			}
		}	
function changsho2(){
		var a=document.getElementById("comp2").getElementsByTagName("li");
		var b=false;
			for(var j=0;j<a.length;j++){
				if(b==true){
					a[j].className="changecolor";
					b=false;
					}
					else{
					b=true;
					}//隔行换色效果
			}
		}