react-native-animated-stopwatch-timer

A React Native Stopwatch/Timer component that empowers reanimated worklets to smoothly animate the digit change. Cross-platform, performant, with all layout animations executed on the UI thread at 60FPS. Compatible with Expo.

• How it is built
• Features
• Preview
• Try it out
• Installation
• Modes
• Usage
• Props
• Methods
• Contributing
• License

How it is built

Want to learn about the inner workings? Check out this deep dive that delves into the beauty of custom layout animations: Custom Layout Animations with Reanimated

Features

• 🔥 Performant: all digit animations are executed on the UI thread
• ⚙️ Highly configurable: easily control its behaviour via props, like animation parameters and styles
• ⌚ Dual mode: use it as a stopwatch or timer
• 📱 Expo compatible: no need to eject to enjoy this component
• 🛠️ Type safe: fully written in TS
• 💻 Snack example: a snack link is provided so you can try it out in your browser

Preview

stopwatch.mp4

Try it out

🧑‍💻 Run the snack example app to see it in action. The source code for the example is under the /example folder.

Installation

npm install react-native-animated-stopwatch-timer

You also need to install react-native-reanimated 2.5.x or higher.

npm install react-native-reanimated

If you are installing reanimated on a bare React Native app, you should also follow these additional installation instructions.

Modes

You can use this component in two different modes:

• Stopwatch: The timer starts counting up from 0 (default).
• Timer: The timer starts counting down from a given time. Use the mode prop and set it to "timer".

Usage

import { useRef } from 'react';
import StopwatchTimer, {
  StopwatchTimerMethods,
} from 'react-native-animated-stopwatch-timer';

const App = () => {
  const stopwatchTimerRef = useRef<StopwatchTimerMethods>(null);

  // Methods to control the stopwatch
  function play() {
    stopwatchTimerRef.current?.play();
  }

  function pause() {
    stopwatchTimerRef.current?.pause();
  }

  function reset() {
    stopwatchTimerRef.current?.reset();
  }

  return <StopwatchTimer ref={stopwatchTimerRef} />;
};

Props

Name	Required	Type	Description
mode	no	stopwatch or timer	Whether the component should work as a stopwatch or as a timer. Defaults to stopwatch
initialTimeInMs	no	number	Initial time in miliseconds
onFinish	no	() => void	Callback executed when the timer reaches 0 (only when working in timer mode and initialTimeInMs prop is provided)
trailingZeros	no	0, 1 or 2	If 0, the component will only display seconds and minutes. If 1, the component will display seconds, minutes, and a hundredth of ms. If 2, the component will display seconds, minutes, and tens of ms. Defaults to 1
animationDuration	no	number	The enter/exit animation duration in milliseconds of a digit. Defaults to 80
animationDelay	no	number	The enter/exit animation delay in milliseconds of a digit. Defaults to 0
animationDistance	no	number	The enter/exit animation vertical distance in dp of a digit. Defaults to 120
containerStyle	no	StyleProp<ViewStyle>	The style of the stopwatch/timer View container
digitStyle	no	StyleProp<TextStyle>	Extra style applied to each digit, excluding separators (: and ,). This property is useful if the fontFamily has different widths per digit to avoid an unpleasant fluctuation of the total component width as it runs. Check the example app where this is used on iOS's default San Francisco font, which presents this issue.
leadingZeros	no	1 or 2	The number of zeros for the minutes. Defaults to 1
enterAnimationType	no	'slide-in-up' or 'slide-in-down'	Whether the new digit should enter from the top or the bottom
separatorStyle	no	StyleProp<TextStyle>	Extra style applied only to separators. In this case, the colon (:) and the comma (,)
textCharStyle	no	StyleProp<TextStyle>	The style applied to each individual character of the stopwatch/timer
decimalSeparator	no	string	Decimal separator for formatting time. Defaults to a comma ,
intervalMs	no	number	The interval in milliseconds to update the stopwatch/timer. Defaults to 16

Methods

play: () => void

Starts the stopwatch/timer or resumes it if paused. It has no effect if it's already running.

stopwatchTimerRef.current?.play();

pause: () => number

Pauses the stopwatch/timer. It has no effect if it is either paused or reset. The method returns a snapshot of the time elapsed in ms.

stopwatchTimerRef.current?.pause();

reset: () => void

Resets the stopwatch/timer.

stopwatchTimerRef.current?.reset();

getSnapshot: () => number

Returns the current time elapsed in ms.

stopwatchTimerRef.current?.getSnapshot();

stopwatchTimerRef refers to the ref passed to the StopwatchTimer component.

Contributing

See the contributing guide to learn how to contribute to the repository and the development workflow.

License

MIT © Raul Gomez Acuna

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