Vue实现鼠标拖拽元素

<div v-drag >{{ fromData.text }}</div>

  directives: {
    drag: function(el) {
      let dragBox = el;
      dragBox.onmousedown = e => {
        //算出鼠标相对元素的位置
        let disX = e.clientX - dragBox.offsetLeft;
        let disY = e.clientY - dragBox.offsetTop;
        document.onmousemove = e => {
          //用鼠标的位置减去鼠标相对元素的位置，得到元素的位置
          let left = e.clientX - disX;
          let top = e.clientY - disY;
          //移动当前元素
          dragBox.style.left = left + "px";
          dragBox.style.top = top + "px";
        };
        document.onmouseup = e => {
          //鼠标弹起来的时候不再移动
          document.onmousemove = null;
          //预防鼠标弹起来后还会循环（即预防鼠标放上去的时候还会移动）
          document.onmouseup = null;
        };
      };
    }
  },