---
title: "Building Lottie Animations in Adobe After Effects with JavaScript Interaction — Part 1: Dynamic Text Replacement"
description: "Demonstrates how to build a Lottie animation with Adobe After Effects and the Bodymovin plugin, then dynamically swap text layers in Vue using lottie-api."
canonical_url: "https://blog.markkulab.net/en/post/lottie-javascript-interactive"
author: "Mark Ku"
author_url: "https://blog.markkulab.net/en/author/mark-ku"
site: "Mark Ku's Tech Notes"
date_published: "2021-12-17 01:01:01 +0800"
category: "Frontend"
tags: ["lottie", "javascript", "vue", "adobe after effect", "ae", "animation", "frontend"]
language: "en"
license: "CC BY 4.0"
license_url: "https://creativecommons.org/licenses/by/4.0/"
attribution: "when reusing or quoting, credit the author and link back to the original"
---

# Building Lottie Animations in Adobe After Effects with JavaScript Interaction — Part 1: Dynamic Text Replacement

## Building Lottie animations in Adobe After Effects with JavaScript interaction — Part 1: Dynamic text replacement

## Foreword
The company wanted to build a "monkey climbing a tree" mini-game. The trigger was that the existing project already used Lottie animations and the smoothness and feel were great, so I dug deeper into how to build a Lottie mini-game with Adobe After Effects and integrate it with our Vue frontend.

## Prerequisites
1. Install Adobe After Effects
2. Install the [Bodymovin](https://exchange.adobe.com/creativecloud.details.12557.bodymovin.html) plugin (used to export the Lottie JSON)
3. Enable "Allow Scripts to Write Files and Access Network"
![After Effects Edit menu, Preferences and General options highlighted](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/qBAg2lw.png)
Tick "Allow Scripts to write file and network access".
![After Effects Preferences, Scripting & Expressions, Allow Scripts to Write Files](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/7yrXojv.png)

## Let's start building
### First, import a Lottie asset into Adobe After Effects
You can download free Lottie JSON files from [lottiefiles.com](https://lottiefiles.com/search?q=time&category=animations).

![LottieFiles website showing monkey animation and its highlighted download URL](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/D3p5hYV.png)

Back in Adobe After Effects, choose Window > Extensions > Bodymovin.
![After Effects Window menu Extensions Bodymovin highlighted](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/ZQ4aAPc.png)

Click Import Lottie Animation.
![Bodymovin plugin interface, Import Lottie Animation button highlighted in red](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/gyIyKMW.png)

Import the JSON file you just downloaded.
![Bodymovin plugin importing Lottie animation from URL](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/eS2T4XB.png)

Successful import:
![Bodymovin plugin showing successful Lottie animation import from URL](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/mAPQE2h.png)
The animation now appears in the asset library:
![After Effects showing imported monkey animation in project panel](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/JP58uy0.png)

### Embedding a text layer for JavaScript to control
Click the horizontal type tool > type some text > "test".
![Adobe After Effects toolbar with horizontal type tool highlighted](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/coRZDF3.png)

Right-click the text layer > Rename.

![After Effects layer context menu with Rename highlighted](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/NlO1Zym.png)


An important note: because we'll control this through JavaScript, we use `#` as a special suffix in the name — characters after `#` will be converted into an `id`. Example: `test#rate`.

![After Effects UI showing text layer named test rate](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/gbS5dHq.png)

When the animation is finally rendered to the page, the id is bound to the corresponding DOM element.

![SVG code snippet highlighting id= rate attribute in a g element](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/77LUp7j.png)

### Exporting the Lottie JSON animation
Open Bodymovin via Window > Extensions > Bodymovin and follow the steps below.
![Bodymovin plugin interface highlighting Lottie JSON export steps](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/YBTNZPW.png)

★★★★★ Important ★★★★★
When exporting the Lottie animation, you must uncheck "Glyphs" — i.e. remove the embedded fonts. Otherwise the export keeps failing with "Character could not be created" and the text won't be exported as HTML.
![Bodymovin settings dialog with Glyphs option selected](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/QxeOZRV.png)

### We expect to use JavaScript to dynamically replace the text on the layer with the previously assigned id. Here's a Vue example:

```
撰寫 Example.vue
<template>
  <div>
    <div class="flex">
      <div ref="monkey" />
    </div>
  </div>
</template>
<script>

import loApi from 'lottie-api'
import lottie from 'lottie-web'
import { numberFormat } from '@/utils'

export default {
  components: {

  },
  data() {
    return {
      lottieAnimation: null
    }
  },
  created() {

  },
  mounted() {
    this.lottieAnimation = this.loadLottieAnimation()
    let count = 1
    const that = this

    // 每兩秒去修改 rate 裡面的值
    setInterval(() => {
      count = count + 0.01
      var api = loApi.createAnimationApi(that.lottieAnimation)
      var elements = api.getKeyPath('test#rate').getElements() // 查找對象
      var ele = elements[0]
      const result = '' + numberFormat(count, 2) // 修改改傳入的值必須是字元串不能是數字，否則會失敗
      ele.setText(result)
    }, 2000)
  },
  methods: {
    loadLottieAnimation() {
      return lottie.loadAnimation({
        container: this.$refs.monkey, // 掛在到對應的 DOM 節點
        loop: true,
        animationData: require('@/assets/lottie/monkey.json'),
        autoplay: true
      })
    }
  }
}
</script>

```

### Result
![Lottie monkey animation in browser with dynamic text 3.99](https://blog.markkulab.net/content/markku/posts/lottie-javascript-interactive/images/u7pN1F2.png)

[Demo video link](https://www.loom.com/share/c882bb074441462bb1f926f2a39cf7d2)

## Wrap-up
Adobe After Effects, combined with the Lottie API, lets you build interactive frontend animations with ease. It's particularly handy for mini-games — you get a wide range of events and properties to tune, like playback speed, play count, looping, and completion callbacks.

## [Next chapter — Building Lottie animations in Adobe After Effects with JavaScript interaction Part 2: Advanced interactions](https://blog.markkulab.net/2021/12/19/lottie-javascript-interactive-part-2)

---

## About this article and its author

Originally published on [Mark Ku's Tech Notes](https://blog.markkulab.net/en/post/lottie-javascript-interactive)

License: [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) — when reusing or quoting, credit the author and link back to the original

### About the author

**[Mark Ku](https://blog.markkulab.net/en/author/mark-ku)** — Software Solution Provider

- 10+ years senior software engineer, now an AI Builder
- Focused on large-platform architecture — North-American e-commerce, AI SaaS subscription billing
- Combining AI Agents and automation to build evolvable product foundations

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