Vue list animation with Greensock JS hooks: wait for leave to finish before enter

问题

Is there a way to get Vue to wait for elements to leave a list before new ones enter? At the moment, the animation for new elements entering the list plays at the same time as the animation for elements leaving the list:

var SPEED = 3;
	
var app = new Vue({
  el: '.container',
  data: {
    nodes: [
      {id: 0, value: 5, name: "Alan"},
      {id: 1, value: 15, name: "Bob"},
      {id: 2, value: 25, name: "Charles"}
    ]
  },
  methods: {
    enter(el, done) {
      var bar = $(el).children(".bar");
      TweenMax.fromTo(bar, SPEED, {width: 0}, {width: $(el).attr("width") * 10, onComplete: done});
    },
    leave(el, done) {
      var bar = $(el).children(".bar");
      TweenMax.fromTo(bar, SPEED, {width: $(el).attr("width") * 10}, {width: 0, onComplete: done});
    },
    swapBobDave() {
      this.nodes = [
        {id: 0, value: 5, name: "Alan"},
        {id: 2, value: 25, name: "Charles"},
        {id: 3, value: 35, name: "Dave"}
      ];
    },
    reset() {
      this.nodes =  [
        {id: 0, value: 5, name: "Alan"},
        {id: 1, value: 15, name: "Bob"},
        {id: 2, value: 25, name: "Charles"}
      ];
    }
  }
});

body {
  margin: 30px;
  font-family: sans-serif;
}

.bar {
  background-color: pink;
  padding: 10px;
  margin: 10px;
}

<script src="http://cdnjs.cloudflare.com/ajax/libs/gsap/1.19.0/TweenMax.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<div class="container">
  <h1>Vue JS Hooks</h1>

	<transition-group name="list" tag="div" v-on:enter="enter" v-on:leave="leave" v-bind:css="false" appear>
		<div v-for="(node, index) in nodes" v-bind:key="node.id" v-bind:width="node.value">
			<div class="bar" v-bind:style="{width: node.value + '%'}">{{node.name}}</div>		
		</div>
	</transition-group>

	<button type="button" class="btn btn-default" @click="swapBobDave">Add Dave and remove Bob</button>
  <button type="button" class="btn btn-default" @click="reset">Reset</button>
	
</div>

Extra points for explaining why the leaving bar doesn't get to width: 0 before disappearing!

回答1:

It's a transition-group, so every change to the array is a different animation. If you always add an element and then remove another one, you can achieve it using a setTimeout on enter hook, having the same duration of SPEED.

enter(el, done) {

    window.setTimeout( () => { 

       var bar = $(el).children(".bar");

       TweenMax.fromTo(bar, SPEED, {width: 0}, {width: $(el).attr("width") * 10, onComplete: done});

    }, SPEED * 1000 )

},

I also suggest you to alter your array in the following way

swapBobDave() {

    this.nodes.splice(1,1);

    this.nodes.push({id: 3, value: 35, name: "Dave"});

},

Concerning the bar, it reachs width: 0 but there is padding: 10px in the css. To fix it you can add margin directly to the text within, and remove padding on bar.

Hope it helps you.

来源：https://stackoverflow.com/questions/56004995/vue-list-animation-with-greensock-js-hooks-wait-for-leave-to-finish-before-ente

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javascript

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