Vue.js manually trig an animation

HTML

<div id="app">
  
    <transition-group
          name="staggered-scale"
          tag="div"
          :css="false"
          @before-enter="animationBeforeEnter"
          @enter="animationEnter"
          :key="animationTrigger"
          appear>

      <span 
          v-for="i in range" 
          :key="i"
          :data-index="i"
          >
          {{ i }}
      </span>

  </transition-group>
  
  <button @click="animationTrigger = !animationTrigger">run it again</button>
  
</div>

CSS

span { display: inline-block; transition: all 1s ease-in; }

JavaScript

window.app = new Vue({
  el: '#app',
  data(){
    return {
      range : [1,2,3,4,5],
      animationTrigger : false
    }
  },
  methods : {
    animationBeforeEnter(el) {
    	console.log('before eneter', el)
      el.style.transform = 'scale(0.1)';
    },
    animationEnter(el, done) {

      const delay = el.dataset.index * 300;
      
      console.log('on enter', el, delay)
      
      setTimeout(() => {
        el.style.transform = 'scale(1.0)';
        done();
      }, delay);
    }
  }
})