callstack / callstack/react-native-slider

Step between 0 and 1 produces floating point rounding errors

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#742 1 comment 0 reactions 0 assignees View on GitHub
bug report
Dominant language
TypeScript
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Description

## Environment
System:
OS: macOS
Binaries:
Node: v22.16.0
npm: 10.9.2

are you using the new architecture?
No (Expo-managed workflow)

which version of react & react-native are you using?
React: 19.1.0
React Native: 0.81.5
@react-native-community/slider: 5.0.1
Expo SDK: 54.0.17

## Description

when using minimumValue of 0, maximumValue of 1, and a step of 0.1, the value returned by onValueChange shows floating-point precision errors. Instead of returning decimal values (e.g. 0.4), it returns e.g. 0.4000000596046448, this can be seen in the value and the markers. Occurs consistently across iOS and Android in the Expo environment.

## Reproducible Demo
```
import React, { useState } from 'react';
import { View, Text } from 'react-native';
import Slider from '@react-native-community/slider';

export default function App() {
const [value, setValue] = useState(0);

return (

setValue(val)}
/>
Value: {value}

);
}
```

## Potential Fix

Round the computed value before emitting it in onValueChange: `value = parseFloat(value.toFixed(6));`
## Workaround
For a temp workaround users can use:
`onValueChange={(val) => setValue(Math.round(val * 10) / 10)}`

Contributor guide

Open the contributing guide

Research direction

Start by running the provided Expo reproduction with minimumValue 0, maximumValue 1, and step 0.1 on both iOS and Android. Trace where onValueChange receives the computed value, then verify that emitted values and displayed markers use the expected decimal steps without floating-point artifacts.

Written by the indexing model from the issue text.

Assessment

Tech stack
react-native, typescript
Domain
mobile-dev
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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