# Glow Effect on TextInput with Reanimated CSS Animations
# Code with Beto · https://codewithbeto.dev/blog/glow-input-reanimated-css
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## This document

- **Title:** Glow Effect on TextInput with Reanimated CSS Animations
- **Canonical URL:** https://codewithbeto.dev/blog/glow-input-reanimated-css
- **Agents export:** https://codewithbeto.dev/blog/glow-input-reanimated-css/agents.txt
- **Author:** Beto
- **Published:** March 20, 2026
- **Summary:** A simple glow effect on a React Native TextInput using Reanimated's new CSS animation keyframes and boxShadow.
- **Access tier:** public (full article in this file)

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---

# Glow Effect on TextInput with Reanimated CSS Animations

Subtle UI feedback makes an app feel alive. One of the simplest ways to add polish to a text input is a glow that activates when the user starts typing.

With [Reanimated's CSS animation support](https://docs.swmansion.com/react-native-reanimated/docs/category/css-animations), you can do this in a few lines, no `useSharedValue`, no `useAnimatedStyle`, just keyframes and `boxShadow`.

## The Approach

The idea is straightforward:

1. Define two keyframe animations: one that fades a `boxShadow` in and one that fades it out.

```tsx
const glowIn: CSSAnimationKeyframes = {
  from: { boxShadow: `0 0 0 0 ${GLOW_COLOR}00` },
  to: { boxShadow: `0 0 32px 4px ${GLOW_COLOR}80` },
};

const glowOut: CSSAnimationKeyframes = {
  from: { boxShadow: `0 0 32px 4px ${GLOW_COLOR}59` },
  to: { boxShadow: `0 0 0 0 ${GLOW_COLOR}00` },
};
```

2. Toggle between them based on whether the input has text.

```tsx
const [text, setText] = useState("");
const hasText = text.length > 0;

return (
  <Animated.View
    style={{
      animationName: hasText ? glowIn : glowOut,
    }}
  />
);
```

3. Wrap the `TextInput` in an `Animated.View` and apply the animation declaratively via style props.

```tsx
import { useState } from "react";
import { StyleSheet, TextInput, View } from "react-native";
import Animated, { type CSSAnimationKeyframes } from "react-native-reanimated";

const GLOW_COLOR = "#6C63FF";

const glowIn: CSSAnimationKeyframes = {
  from: { boxShadow: `0 0 0 0 ${GLOW_COLOR}00` },
  to: { boxShadow: `0 0 32px 4px ${GLOW_COLOR}80` },
};

const glowOut: CSSAnimationKeyframes = {
  from: { boxShadow: `0 0 32px 4px ${GLOW_COLOR}59` },
  to: { boxShadow: `0 0 0 0 ${GLOW_COLOR}00` },
};

export function GlowInput() {
  const [text, setText] = useState("");
  const hasText = text.length > 0;

  return (
    <View style={styles.container}>
      <Animated.View
        style={[
          styles.glow,
          {
            animationName: hasText ? glowIn : glowOut,
            animationDuration: hasText ? "400ms" : "500ms",
            animationFillMode: "forwards",
            animationTimingFunction: "ease-out",
          },
        ]}
      >
        <TextInput
          autoFocus
          value={text}
          onChangeText={setText}
          placeholder="Type something..."
          placeholderTextColor="#999"
          cursorColor={GLOW_COLOR}
          style={styles.input}
        />
      </Animated.View>
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: "center",
    paddingHorizontal: 24,
  },
  glow: {
    borderRadius: 999,
  },
  input: {
    color: "#fff",
    fontSize: 18,
    fontWeight: "500",
    paddingHorizontal: 20,
    paddingVertical: 16,
    backgroundColor: "#1c1c1e",
    borderRadius: 999,
    borderWidth: 1,
    borderColor: "#333",
  },
});
```

## Tips

- **Swap the color**, change `GLOW_COLOR` to match your app's accent color. Red for errors, green for valid state, whatever fits.
- **Adjust intensity**, the `32px` blur radius and `4px` spread control how dramatic the glow feels. Dial them down for something more subtle.
- **Trigger on focus instead**, replace the `hasText` check with `onFocus` / `onBlur` state if you want the glow to activate on tap rather than on input.

## Want to go deeper?

The React Native course includes a lesson on **Animations and Gestures**: Reanimated helpers (`withTiming`, `withSpring`, and related APIs) and gesture types from React Native Gesture Handler, with a small app example you can reference.

**Animations and Gestures**

Reanimated animation helpers, gesture-handler gesture types (pan, tap, pinch, and more), and how they combine in interactive UIs. About 35 minutes.

[Open the lesson](https://codewithbeto.dev/rnCourse/animationsAndGestures)

For the full curriculum, see the [React Native course](/learn).

I also share practical tips, experiments, and updates in my [newsletter](/newsletter) if you want to stay in the loop.

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