<div style="position:absolute;width:100px;height:100px;border:1px solid red" v-drag="{set:set}"></div>

methods:{
set(x,y){
this.data.x=x;
this.data.y=y;
}
},
directives:{
// 拖动的自定义指令
drag(el,binding){
//el为拖动的元素
var oDiv =el;
 oDiv.onmousedown = function(e){
  e.preventDefault();
     e.stopPropagation();
  var disX = e.offsetX;
  var disY = e.offsetY;
  document.onmousemove = function(e){
  e.preventDefault();
e.stopPropagation();
  var x=e.pageX-disX;
  var y=e.pageY-disY
   oDiv.style.left=x
oDiv.style.top=y
  // 通过传参的形式，将methods中的函数传进来，以此来改变data中的值
  binding.value.set(x,y)
  };
  document.onmouseup = function(){
  document.onmousemove=null;
  document.onmouseup=null;
  };
 };
}
},