jQuery判断网页中的id是否有重复的

From:http://blog.csdn.net/china_skag/article/details/6915323

判断网页中的ID是否有重复的:指定ID判断

$(function(){    
    $("body [id]").each(function(){    
         var ids = $(this).attr("id");    
          if( $("body [id="+ids+"]").length >= 2 ){    
                         alert("id为"+ids+" 的重复了。");    
        }    
    });    
})  

判断网页中的ID是否有重复的：不指定ID判断

function chkid() {
        var did = {}
        divs = document.getElementsByTagName("*");
        for (var i = 0, l = divs.length; i < l; i++) {
            divs[i].getAttribute("id")
                ? did[divs[i].getAttribute("id")] === undefined
                    ? did[divs[i].getAttribute("id")] = 0
                    : did[divs[i].getAttribute("id")]++
                : 0;
        }
        for (var i in did) {
            did[i]
                ? alert("id " + i + "重复了" + (did[i] + 1) + "次")
                : 0;
        }
    }