<script type="text/javascript"> 
  
$(document).ready(function(){ 
alert($('#dom0').find('.mo')); });
</script>  直接这样没问题 可是 放在事件里<script type="text/javascript"> 
  
$(document).ready(function(){$('#msave').click(function(){ 
 
alert($('#dom0').find('.mo')); 
}); });
</script>
就不行了 为空或不是对象了!

解决方案 »

  1.   

    首先要确定有没有ID为msave、dom0的元素如果有,则说明指定元素在页面刚刚加载完毕时有,之后就没有了(可能是执行了其它代码,删除了元素)
      

  2.   

    楼主上HTML代码。。
    为空或不是对象了!是哪行
      

  3.   

    哦 问题找到了 执行 后面的js 就出现这样的错误了
    <script>
     
    var dragobj={}
    window.onerror=function(){return false}
    var domid=14
    function on_ini(){
            String.prototype.inc=function(s){return this.indexOf(s)>-1?true:false}
            var agent=navigator.userAgent
            window.isOpr=agent.inc("Opera")
            window.isIE=agent.inc("IE")&&!isOpr
            window.isMoz=agent.inc("Mozilla")&&!isOpr&&!isIE
            if(isMoz){
                    Event.prototype.__defineGetter__("x",function(){return this.clientX+2})
                    Event.prototype.__defineGetter__("y",function(){return this.clientY+2})
            }
            basic_ini()
    }
    function basic_ini(){
            window.$=function(obj){return typeof(obj)=="string"?document.getElementById(obj):obj}
            window.oDel=function(obj){if($(obj)!=null){$(obj).parentNode.removeChild($(obj))}}
    }
    window.oDel=function(obj){if($(obj)!=null){$(obj).parentNode.removeChild($(obj))}}
    window.onload=function(){
            on_ini()
            var o=document.getElementsByTagName("h1")
            for(var i=0;i<o.length;i++){
                    o[i].onmousedown=addevent;
                    //添加折叠和关闭按钮
                    var tt = document.createElement("div");
                    tt.style.cssText = "float:left";
                    
                    var span = document.createElement("span");
                    span.innerHTML = "--"+o[i].innerHTML;
                    span.style.cssText = "cursor:default;";
                    span.onmousedown = minusDiv;
                    tt.appendChild(span);
                    
                    var close = document.createElement("div");
                    close.innerHTML = "X";
                    close.style.cssText = "cursor:default;float:right";
                    close.onmousedown = closeDiv;
                    o[i].innerHTML = "";
                    o[i].appendChild(tt);
                    o[i].appendChild(close);
            }
    }
    //折叠或者显示层
    function minusDiv(e)
    {
            e=e||event
            var nr = this.parentNode.parentNode.nextSibling;        //取得内容层
            nr.style.display = nr.style.display==""?"none":"";
    }
    //移出层
    function closeDiv(e)
    {
            e=e||event
            var mdiv = this.parentNode.parentNode;        //取得目标层
            oDel(mdiv);
    }
    function addevent(e){  
                            if(dragobj.o!=null)
                                    return false
                            e=e||event
                            dragobj.o=this.parentNode
     
                            dragobj.xy=getxy(dragobj.o)
                            dragobj.xx=new Array((e.x-dragobj.xy[1]),(e.y-dragobj.xy[0]))
                            //dragobj.o.className = 'dragging';
                            dragobj.o.style.width=dragobj.xy[2]+"px"
                            dragobj.o.style.height=dragobj.xy[3]+"px"
                            dragobj.o.style.left=(e.x-dragobj.xx[0])+"px"
                            dragobj.o.style.top=(e.y-dragobj.xx[1])+"px"
                            dragobj.o.style.position="absolute"
                            dragobj.o.style.filter='alpha(opacity=60)';                //添加拖动透明效果
                            var om=document.createElement("div")
                            dragobj.otemp=om
                            om.style.width=dragobj.xy[2]+"px"
                            om.style.height=dragobj.xy[3]+"px"
                            om.style.border = "1px dashed red";        //ikaiser添加,实现虚线框
                            dragobj.o.parentNode.insertBefore(om,dragobj.o)
                            return false
    }
    document.onselectstart=function(){return false}
    window.onfocus=function(){document.onmouseup()}
    window.onblur=function(){document.onmouseup()}
    document.onmouseup=function(){
            if(dragobj.o!=null){
                    dragobj.o.style.width="auto"
                    dragobj.o.style.height="auto"
                    dragobj.otemp.parentNode.insertBefore(dragobj.o,dragobj.otemp)
                    dragobj.o.style.position=""
                    oDel(dragobj.otemp)
                    dragobj={}
            }
    }
    document.onmousemove=function(e){
            e=e||event
            if(dragobj.o!=null){
                    dragobj.o.style.left=(e.x-dragobj.xx[0])+"px"
                    dragobj.o.style.top=(e.y-dragobj.xx[1])+"px"
                    createtmpl(e, dragobj.o)        //传递当前拖动对象
            }
    }
    function getxy(e){
            var a=new Array()
            var t=e.offsetTop;
            var l=e.offsetLeft;
            var w=e.offsetWidth;
            var h=e.offsetHeight;
            while(e=e.offsetParent){
                    t+=e.offsetTop;
                    l+=e.offsetLeft;
            }
            a[0]=t;a[1]=l;a[2]=w;a[3]=h
      return a;
    }
     function inner(o,e){
            var a=getxy(o)
            if(e.x>a[1]&&e.x<(a[1]+a[2])&&e.y+document.documentElement.scrollTop>a[0]&&e.y+document.documentElement.scrollTop<(a[0]+a[3])){
                    if(e.y+document.documentElement.scrollTop<(a[0]+a[3]/2))
                            return 1;
                    else
                            return 2;
            }else
                    return 0;
    }
    //将当前拖动层在拖动时可变化大小,预览效果
    function createtmpl(e, elm){
            for(var i=0;i<domid;i++){
                    if(document.getElementById("m"+i) == null)        //已经移出的层不再遍历
                            continue;
                    if($("m"+i)==dragobj.o)
                            continue
                    var b=inner($("m"+i),e)
                    if(b==0)
                            continue
                    dragobj.otemp.style.width=$("m"+i).offsetWidth
                    elm.style.width = $("m"+i).offsetWidth;
                    //1为下移,2为上移
                    if(b==1){
                            $("m"+i).parentNode.insertBefore(dragobj.otemp,$("m"+i))
                    }else{
                            if($("m"+i).nextSibling==null){
                                    $("m"+i).parentNode.appendChild(dragobj.otemp)
                            }else{
                                    $("m"+i).parentNode.insertBefore(dragobj.otemp,$("m"+i).nextSibling)
                            }
                    }
                    return
            }
            for(var j=0;j<2;j++){//
                    if($("dom"+j).innerHTML.inc("div")||$("dom"+j).innerHTML.inc("DIV"))
                            continue
                    var op=getxy($("dom"+j))
                    if(e.x>(op[1]+10)&&e.x<(op[1]+op[2]-10)){
                            $("dom"+j).appendChild(dragobj.otemp)
                            dragobj.otemp.style.width=(op[2]-10)+"px"
                    }
            }
    }function add_div()
    {
            var o=document.createElement("div")
            o.className="mo"
            o.id="m"+domid
            $('dom0').appendChild(o)
            o.innerHTML="<h1>dom"+domid+"</h1><div class=nr></div>"
            o.getElementsByTagName("h1")[0].onmousedown=addevent
            domid++
    }
     
    </script>  
      

  4.   

    alert($('#dom0 .mo').text()); 
    试试