1.在vue中要获取event事件对象 在绑定事件时要利用$event作为参数传递。

<template>
  <div id="imgBox">
    <!-- 碎片 -->
    <div id="slidImg">
      <img src="https://5-2ebf-4838-9ece-bde9690e8134.png" alt="">
    </div>
    <!-- 大图 -->
    <div id="img">
      <img src="https:/2-399de2f59fca.png" alt="">
    </div>
    <!-- 滑块部分 -->
    <div id="sliding">
      <div class="bg"></div>
      <span id="huakuai" @mousedown='mousedownFn($event)' @mousemove='mousemoveFn($event)' @mouseup='mouseupFn($event)'></span>
    </div>
  </div>
</template>

2.css的部分 我用的是sass书写样式，sass里变量要类似这样写 $move: var(--moveLeft, 0px);js要修改sass中的变量 就需要用到.style.setProperty('css变量名',新值)，--moveLeft就是css变量名。

2.css的部分 我用的是sass书写样式，sass里变量要类似这样写 $move: var(--moveLeft, 0px);js要修改sass中的变量 就需要用到.style.setProperty('css变量名',新值)，--moveLeft就是css变量名。

<script>
import axios from 'axios'
export default {
  data() {
    return {
      isMove:false
    };
  },

  methods:{
    mousedownFn(e){
    this.isMove = true;
    },
    mousemoveFn(e){
        const box = document.getElementById("imgBox");
  const sliding = document.getElementById("sliding");
  const huakuai = document.getElementById("huakuai");
  const img=document.getElementById('img');
 
        if (this.isMove) {
      const offsetLeft = sliding.getBoundingClientRect().left;
      const maxLeft = sliding.getBoundingClientRect().width;
      const btnWidth = huakuai.getBoundingClientRect().width;
     
      if (e.clientX > offsetLeft + btnWidth / 2) {
        if (e.clientX < offsetLeft + maxLeft - btnWidth / 2) {
          // greenWid
          box.style.setProperty(
            "--moveLeft",
            `${e.clientX - offsetLeft - btnWidth / 2}px`
          );
       
        }
      }
    }
    },
    mouseupFn(e){
  // console.log("离开", e);
    this.isMove = false;
    }

  }
};
</script>
<style lang='scss' scoped>
#imgBox {
  $imgHeight: 300px;
  $slidW: 100%;
  $spanWd: 80px;
  $move: var(--moveLeft, 0px);
  height: 500px;
  width: 600px;
  padding: 10px;
  box-sizing: border-box;
  background-color: rgb(240, 230, 229);
  position: relative;
  img{
    width: 100%;
    height: 100%;
  }
  #img {
    margin-left: 20%;
    width:auto;
    // height: 140px;
    // background-color: rgb(175, 99, 91);
  }
  #slidImg {
    position: absolute;
    width: auto;
    height: 61px;
    left: $move;
    top: 120px;
    // background-color: sandybrown;
       transition:all 0s ease;
  }
  #sliding {
    position: relative;
    margin-top: 30px;
    width: $slidW;
    height: 60px;
    border-radius: 6px;
    background-color: rgb(219, 219, 219);
    overflow: hidden;
    .bg{
      position: absolute;
      height: 100%;
      width: $move;
      left: 0;
      top: 0;
      background-color: rgb(49, 185, 79);
          transition:all 0s ease;
    }
    span {
      display: inline-block;
      position: absolute;
      left: $move;
      height: 60px;
      width: $spanWd;
      border-radius: 5px;
      background-color: rgb(255, 255, 255);
      background-image: url('../assests/右双箭头.png');
      background-size: 40px;
      background-repeat: no-repeat;
      background-position: center;
     
    transition:all 0s ease;
    }
  }
}
</style>

嘿嘿嘿~~~ 一个小小的滑动拼图就这样完成啦！！！！