<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script type="text/javascript">
 function test(){
             alert("OKOKOK");
        }
        function test1(){
             alert("false");
        }
window.onload=test;
                if (typeof window.onload == "function") {
                var existingOnload = window.onload;
                window.onload = function() {
                    existingOnload();
                    test();
                } //end existing onload handler
            } else{
                window.onload = function(){
   test1();
}
          }
</script>
</head><body>
</body>
</html>
改成这样试试
你没指定window.onload  所以返回的是object  不是function