为什么这个jq的拖拽只能执行一次呢？求大神帮看一下

Question

HTML代码：<div></div>CSS代码：div{         width: 100px;         height: 100px;         background: red;         position: absolute; }jq代码：<script type="text/javascript">     $(function(){              var disX,disY;              $("div").mousedown(function(event){                          /*鼠标距离红方块边缘的距离*/                          disX=event.pageX - $("div").offset().left;                          disY=event.pageY - $("div").offset().top;              });              $(document).mousemove(function(event){                      $("div").css({                      "left":event.pageX - disX,                      "top":event.pageY - disY                      });              });              $(document).mouseup(function(){                      $(document).off();              });              return false;     }) </script>——————————————————————————————修改了一下，这样就可以了：<script type="text/javascript">         $(function(){                     var disX,disY;                     $("div").mousedown(function(event){                                                      disX=event.pageX - $(this).offset().left;                                 disY=event.pageY - $(this).offset().top;                                                                  $(document).mousemove(function(event){                                                 $("div").css({                                                         "left":event.pageX - disX ,                                                         "top":event.pageY - disY                                                 });                                 });                                                                  $(document).mouseup(function(){                                                  $(document).off("mousemove");                                 });                                                                  return false;                                          });                      })</script>

Answer 1

$(document).off();

在你$(document).mouseup的方法里，执行了以上代码，导致document上的事件全部被移除。那么

$(document).mousemove和$(document).mouseu全部都被移除了。只剩下可怜的$("div").mousedown
存在，当然就不能有第二次了。所以，如果想要做出你要的功能现在的代码结构是不正确的。