移动端实现拖拽事件

<template>
<div>
    <div class="floatball" id="floatball"
      @mousedown="down" @touchstart.stop="down"
      @mousemove="move" @touchmove.stop="move"
      @mouseup="end" @touchend.stop="end"
      :style="{top:position.y+'px', left:position.x+'px'}">
      小球球
  </div>
  <!-- <div class="div1"></div> -->
</div>
    

  
</template>

<script>
// 鼠标位置和div的左上角位置 差值
var dx,dy
var screenWidth = window.screen.width
var screenHeight = window.screen.height

export default {
  data() {
    return {
      flags: false,
      position: {
        x: 320,
        y: 60
      },
    }
  },
  

  methods: {
    // 实现移动端拖拽
    down(event){
      this.flags = true;
      var touch ;
      if(event.touches){
          touch = event.touches[0];
      }else {
          touch = event;
      }
      console.log('鼠标点所在位置', touch.clientX,touch.clientY)
      console.log('div左上角位置', event.target.offsetTop,event.target.offsetLeft)
      dx = touch.clientX - event.target.offsetLeft
      dy = touch.clientY - event.target.offsetTop
    },
    move() {
      if (this.flags) {
        var touch ;
        if (event.touches) {
          touch = event.touches[0];
        } else {
          touch = event;
        }
        // 定位滑块的位置
        this.position.x = touch.clientX - dx;
        this.position.y = touch.clientY - dy;
        // 限制滑块超出页面
        // console.log('屏幕大小', screenWidth, screenHeight )
        if (this.position.x < 0) {
          this.position.x = 0
        } else if (this.position.x > screenWidth - touch.target.clientWidth) {
          this.position.x = screenWidth - touch.target.clientWidth
        }
        if (this.position.y < 0) {
          this.position.y = 0
        } else if (this.position.y > screenHeight - touch.target.clientHeight) {
          this.position.y = screenHeight - touch.target.clientHeight
        }
        //阻止页面的滑动默认事件
        document.addEventListener("touchmove",function(){
            event.preventDefault();
        },false);
      }
    },
    //鼠标释放时候的函数
    end(){
      console.log('end')
      this.flags = false;
    },

   }
 
}
</script>

<style>
  .floatball{
    color:white;
    height:50px;
     50px;
    padding: 5px;
    z-index: 990;
    position: fixed;
    top: 60px;
    right: 320px;
    border-radius: 50%;
    background-color: rgba(29, 157, 237,0.8);
    line-height: 50px;
  }
.div1{
     100px;
    height: 100px;
    background: red;
}
</style>