定位输入提示框

  首先输入一个输入对象，如果一个输入框是<input type = 'text' name='goodman' id='goodman'  />
     position($('goodman'));
  /**
     * 定位提示框
     */
    var position = function(o){
   
        var top = o.offsetTop;
        var height = o.clientHeight;
        var left = o.offsetLeft;
        while (o = o.offsetParent) {
            top += o.offsetTop;
            left += o.offsetLeft;
        }
        divTop.style.top = (top + height + 6) + 'px';
        divTop.style.left = left + 'px';
        divTop.style.display = "block";
       
        div.style.top = (divTop.offsetTop + divTop.clientHeight) + 'px';
        div.style.left = left + 'px';
        div.style.display = "block";
       
        divBottom.style.top = (div.offsetTop + div.clientHeight - 1) + 'px';
        divBottom.style.left = left + 'px';
        divBottom.style.display = "block";
    };