vue.js加入购物车小球动画

    data(){
      return {
        balls: [
          {
            show: false
          },
          {
            show:  false
          },
          {
            show:  false
          },
          {
            show:  false
          },
          {
            show:  false
          }
        ],
        dropBalls:[]
      }
    },

methods: {
      drop(el) { 
      //触发一次事件就会将所有小球进行遍历
        for (let i = 0; i < this.balls.length; i++) {
          let ball = this.balls[i];
          if (!ball.show) { //将false的小球放到dropBalls
            ball.show = true;
            ball.el = el; //设置小球的el属性为一个dom对象
            this.dropBalls.push(ball); 
            return;
          }
        }
      },

      beforeEnter(el){ //这个方法的执行是因为这是一个vue的监听事件
        let count = this.balls.length;
        while (count--) {
          let ball = this.balls[count];
          if (ball.show) {
            let rect = ball.el.getBoundingClientRect(); //获取小球的相对于视口的位移(小球高度)
            let x = rect.left - 32;
            let y = -(window.innerHeight - rect.top - 22); //负数,因为是从左上角往下的的方向
            el.style.display = ''; //清空display
            el.style.webkitTransform = `translate3d(0,${y}px,0)`; 
            el.style.transform = `translate3d(0,${y}px,0)`;
            //处理内层动画
            let inner = el.getElementsByClassName('inner-hook')[0]; //使用inner-hook类来单纯被js操作
            inner.style.webkitTransform = `translate3d(${x}px,0,0)`;
            inner.style.transform = `translate3d(${x}px,0,0)`;
          }
        }
      },

      enter(el, done) { //这个方法的执行是因为这是一个vue的监听事件
        /* eslint-disable no-unused-vars */
        let rf = el.offsetHeight; //触发重绘html
        this.$nextTick(() => { //让动画效果异步执行,提高性能
          el.style.webkitTransform = 'translate3d(0,0,0)';
          el.style.transform = 'translate3d(0,0,0)';
          //处理内层动画
          let inner = el.getElementsByClassName('inner-hook')[0]; //使用inner-hook类来单纯被js操作
          inner.style.webkitTransform = 'translate3d(0,0,0)';
          inner.style.transform = 'translate3d(0,0,0)';
          el.addEventListener('transitionend', done); //Vue为了知道过渡的完成，必须设置相应的事件监听器。
        });
      },

      afterEnter(el) { //这个方法的执行是因为这是一个vue的监听事件
        let ball = this.dropBalls.shift(); //完成一次动画就删除一个dropBalls的小球
        if (ball) {
          ball.show = false;
          el.style.display = 'none'; //隐藏小球
        }
      }
    }

    .ball-container
      .ball
        position fixed
        left: 32px
        bottom: 22px
        z-index:200
        transition: all .6s cubic-bezier(0.49, -0.29, 0.75, 0.41)
        .inner
          width 16px
          height 16px
          border-radius 50%
          background rgb(0,160,220)
          transition: all .6s linear