js开始就启动所有函数

function addLoadEvent(func) {
    var oldonload = window.onload;
    if (typeof window.onload !== 'function') {
	     window.onload = func;
   }
 else {
     window.onload = function () {
	        if (oldonload) {
  	          oldonload();
   	     }
  	      func();
   	  }
	 }
	}