This article summarizes how to animate the display when adding to an array in Vue.

How to Animate When Adding to an Array in Vue

Animating in Vue

Vue provides convenient components for animating elements, such as when toggling visibility with v-if or v-show. One of these components is:

<Transition></Transition>

How to Use Vue's Transition, Explained Simply

In most cases, this will work, but this article focuses on the pattern when working with arrays.

Implementation

Clicking the button adds an element to the array, making the added element float up with a smooth animation.

<template>
  <div class="container">
    <button @click="addArray">Increase</button>
    <!-- Surround the growing array part with the transition-group tag -->
    <!-- Specifies the animation name as 'list' -->
    <transition-group name="list" tag="div">
      <div v-for="a in array" :key="a.id">
        <p>{{ a.id }}: {{ a.text }}</p>
      </div>
    </transition-group>
  </div>
</template>

<script>
export default {
  data() {
    return {
      // Initial values
      array: [
        {
          id: 1,
          text: "Text 1",
        },
        {
          id: 2,
          text: "Text 2",
        },
        {
          id: 3,
          text: "Text 3",
        },
      ],
    }
  },
  methods: {
    addArray() {
      // Sample function that adds an arbitrary object
      this.array.push({
        id: 4,
        text: "Text 4",
      })
    },
  },
}
</script>

<style scoped>
.container {
  margin: 100px;
  width: 100%;
}
/* Sets up an animation called 'list' */
.list-enter-active,
.list-leave-active {
  transition: all 1s;
}
.list-enter, .list-leave-to /* .list-leave-active for below version 2.1.8 */ {
  opacity: 0;
  transform: translateY(30px);
}
</style>

Explanation of the Implementation

Using the <transition-group> Component

<transition-group name="list" tag="div">
  <div v-for="a in array" :key="a.id">
    <p>{{ a.id }}: {{ a.text }}</p>
  </div>
</transition-group>

When working with arrays, displaying elements often involves using v-for. By using the <TransitionGroup> component instead of the <Transition> component, you can implement animations.

Specify a Name for transition-group

In this case, name="list" assigns the name "list" to the animation.

Specify a Tag for transition-group

In this case, tag="div" wraps the items in a div tag.

Write the Animation Details in the Style Section

/* Sets up an animation called 'list' */
.list-enter-active,
.list-leave-active {
  transition: all 1s;
}
.list-enter, .list-leave-to /* .list-leave-active for below version 2.1.8 */ {
  opacity: 0;
  transform: translateY(30px);
}

In this setup, items appear to float up from below as they are added. By modifying the CSS, you can create various animations.

Vue Transition Guide

About Animations

Web animations add movement to elements on a web page or application, improving user experience and facilitating information flow. However, if not designed properly, animations can also make things more difficult for users.

Benefits

Visual Guidance

Animations can guide users' attention naturally. For example, hover effects on buttons or fade-in notifications make actions or information stand out.

Enhanced User Experience

Animations make interactions enjoyable and help make apps or websites feel more intuitive, increasing user engagement. Smooth animations also convey reliability and a sense of quality.

Smooth Information Delivery

Showing or hiding elements with animation allows for a step-by-step presentation of information, making it easier for users to process. For instance, a loading spinner provides feedback and reassurance while waiting.

Reinforced Branding

Animations tailored to a brand's identity help make a website more memorable and convey personality.

Drawbacks

Performance Degradation

Heavy animations can increase loading times and may be slow on mobile devices, affecting usability and causing a delayed feel.

Usability Impact

Excessive or distracting animations may irritate users or disrupt their understanding of the interface. Flashing or flickering animations, in particular, can be distracting and confusing.

Accessibility Issues

For users with visual or cognitive impairments, motion-heavy content may be overwhelming. Some animations can even cause motion sickness or discomfort, especially if "Reduce Motion" settings aren't respected.

Increased Development and Maintenance Costs

Implementing animations requires extra code and design considerations. Ensuring browser compatibility and coordinating with other elements can be complex, adding to long-term maintenance.

Conclusion

This article covered how to animate the display when adding to an array in Vue.

Vue provides numerous convenient components, and using <TransitionGroup> makes it easy to implement this feature. I hope this article helps someone.