cfyme

window.onload = function(){
        var str = "";
        var a = "";
        //var a = 執行代碼，返回第一個重復的id;
        var tags = document.getElementsByTagName("*");
        for(var i = tags.length-1; i > -1; i--)
        {
             var o = tags[i];
             var id = o.id;
             if (id && document.getElementById(id) != o)
             {
                   a = id;
                   str+= a + ",";
             }
        }
        alert(str);         
}