jQuery判断网页中的id是否有重复的

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

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;
    }
}