交叉

<template>
  <div class="about">
    <div class="line"></div>
    <div class="line active"></div>
    <div class="small-ball" @touchstart="FnStart"></div>
    <div class="small-ball ac" @touchstart="FnStart"></div>
  </div>
</template>

<script>
export default {
  data() {
    return {};
  },
  methods: {
    FnStart(ev) {
      this.startX = ev.changedTouches[0].pageX - ev.target.offsetLeft;
      this.parent=ev.target.parentNode;
      this.child=this.parent.children;
      this.oW=this.parent.offsetWidth-ev.target.offsetWidth;

      document.ontouchmove = this.FnMove;
      document.ontouchend = this.FnEnd;
    },
    FnMove(ev) {
      this.L = ev.changedTouches[0].pageX - this.startX;

      if(this.L<0)this.L=0;
      if(this.L>this.oW)this.L=this.o