---
title: "Icons that react"
description: "Lesson 12.3 of Creator Terminal's lesson films (Use cases): Make your app's save button fill with a pop when it's tapped and empty on the next tap, try it as a player would, and ship it."
canonical: "https://terminal.lottiefiles.com/icons-that-react/"
last_updated: 2026-11-04
---

# Icons that react

> Lesson 12.3 of Creator Terminal's lesson films (Use cases): Make your app's save button fill with a pop when it's tapped and empty on the next tap, try it as a player would, and ship it.

- The film (1:34): https://terminal.lottiefiles.com/media/12.3-icons-that-react/01fe37ff6e40/12.3-icons-that-react.mp4
- Vertical cut: https://terminal.lottiefiles.com/media/12.3-icons-that-react/2e845d978708/12.3-icons-that-react-vertical.mp4
- Captions: https://terminal.lottiefiles.com/media/12.3-icons-that-react/997725de67a5/12.3-icons-that-react.vtt
- The page: https://terminal.lottiefiles.com/icons-that-react/

## In this lesson

### The save button (0:07)

Here's the heart people tap to save a trip. As it stands, it's a picture. A tap does nothing, so nobody's sure it worked.

### Ask for the reaction (0:17)

Let's give it a reaction. Press slash, and say what a tap does, and what the next one does: the heart fills coral with a pop and a little burst, and another tap empties it again.

### Watch it work (0:32)

Send it. It draws a burst of eight dots, and keys the fill to swell from the heart's centre. Then it marks four moments, empty, filling, saved and emptying, and builds a state machine: a tap moves it from one to the next. It even taps the button itself to check the machine, and pins a note with a question for us.

### Tap it (0:53)

Close the copilot, and press control P to try it. The stage becomes the player. Tap the heart. It fills with a pop, and the dots burst out. On the right is what happened: the tap set saved to true, and sent the app an event, saved.

### Tap again (1:10)

Tap it again, and it empties. The coral drains back into the heart, quietly this time.

### Ship the reaction (1:16)

Press escape to stop trying. A dotLottie carries the machine to the app, so click export, then dotLottie, then Export file. Just three kilobytes.