Router.prototype.goBack = function () {
 this.isBack = true
 window.history.go(-1)
}
const router = new Router({
 routes: [
  {
   path: '/',
   name: 'PageTransition', 
   component: PageTransition, // 引入页面切换组件
   children: [{
    path: '',
    component: Index // 父路由访问页面，例如，访问www.aaa.com/ 显示的是Index组件
   }, {
    path: '/pageA',
    component: PageA // 子路由组件 例如，访问www.aaa.com/pageA 显示为PageA
   }, {
    path: '/pageB',
    component: PageB // 子路由组件 例如，访问www.aaa.com/pageB 显示为PageB
   }]
  }
 ]
})

$router.go(-1) 

// 增强原方法，好处是旧的业务模块不需要任何变动
Router.prototype.go = function () {
 this.isBack = true
 window.history.go(-1)
}

// 或者你可以新建一个方法
Router.prototype.goBack = function () {
 this.isBack = true
 this.go(-1)
}

beforeRouteUpdate (to, from, next) {
 // 如果isBack为true时，证明是用户点击了回退，执行slide-right动画
  let isBack = this.$router.isBack
  if (isBack) {
   this.transitionName = 'slide-right'
  } else {
   this.transitionName = 'slide-left'
  }
  // 做完回退动画后，要设置成前进动画，否则下次打开页面动画将还是回退
  this.$router.isBack = false
   next()
}

 <transition :name="transitionName">
  <router-view class="child-view"></router-view>
 </transition>

.child-view {
 position: absolute;
 width:100%;
 transition: all .8s cubic-bezier(.55,0,.1,1);
}
.slide-left-enter, .slide-right-leave-active {
 opacity: 0;
 -webkit-transform: translate(50px, 0);
 transform: translate(50px, 0);
}
.slide-left-leave-active, .slide-right-enter {
 opacity: 0;
 -webkit-transform: translate(-50px, 0);
 transform: translate(-50px, 0);
}

const router = new Router({
 routes: [
  {
   path: '/',
   name: 'PageTransition',
   component: PageTransition,
   children: [{
    // 该路由为父路由的默认路由
    path: '',
    component: Index
   }, {
    path: '/pageA',
    component: PageA
   }, {
    path: '/pageB',
    component: PageB
   }]
  }
 ]
})