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3.4.5 • Public • Published

⏱️ React Use Precision Timer

A versatile precision timer hook for React. Doubles as a stopwatch.

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Read the official documentation.


👁️ Live Demo


A React timer hook that calls the provided callback at regular intervals. Can be used as a stopwatch, too.

It's accurate, precise, and includes a rich set of options, functionality, and accessors.

Features include:

  • ⏰ Timeout and timestamp based
    • Based on setTimeout() and Unix times, not ticks.
  • 🎯 Accurate and precise
    • Perfect mean accuracy with no wandering, with sub 10ms callback precision.
  • 💪 Doesn't choke under pressure
    • Resilient to expensive callbacks and low timer delays.
  • 🧰 Versatile
    • Can be used as a timer, one-time delay, or stopwatch. Additional options available.
  • ⏯️ Pause and resume
    • Supports pausing, and tracks cumulative elapsed pause time between resumes.
  • 🌞 Accessors for everything
    • Includes getters for everything under the sun! Know all the things.

🆕 New In Version 3

Version 3 of this package features a complete redesign to reduce unnecessary renders, plus the addition of a new convenience hook.

  • Internally, timer state is now tracked via React refs and timer options are memoized for you. These changes significantly improved performance.
  • The useTimer hook's signature has been changed. The callback is now provided as the second argument, and should be cached using React.useCallback() to optimize render performance. Refer to the Quick Start section below.
  • The useMomentaryBool hook was added.


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Table of Contents


npm i react-use-precision-timer

Quick Start

Repeating Timer

import { useTimer } from "react-use-precision-timer";

In your function component:

const callback = React.useCallback(() => console.log('Boom'), []);
// The callback will be called every 1000 milliseconds.
const timer = useTimer({ delay: 1000 }, callback);

In a handler or effect:


The following functions can be used to control the Timer:

  • timer.start() - Start the timer. If already started, will restart the timer. You can optionally pass a start time in Unix epoch milliseconds.
  • timer.stop() - Stop the timer.
  • timer.pause() - Pause the timer.
  • timer.resume() - Resume the timer.

Refer to Timer for all available functions, including getters for elapsed times.

One-Time Delay

If you'd like to run a callback after a one-time delay, use the helper hook useDelay:

import { useDelay } from 'react-use-precision-timer';

In your function component:

const callback = React.useCallback(() => console.log('Boom'), []);
// Will call once after 1000ms.
const onceTimer = useDelay(1000, callback);

In a handler or effect:


This will call the callback after the provided 1000 millisecond delay only once.


The timer also functions as a stopwatch when no delay is provided. You can use the helper hook useStopwatch:

import { useStopwatch } from "react-use-precision-timer";
const stopwatch = useStopwatch();

Use start(), stop(), pause(), and resume() to control the stopwatch.

Stopwatch is a Timer object. Refer to Timer's getters to retrieve elapsed running time, paused time, and so forth.

Calling start while a stopwatch is already running will restart it.

Momentary Boolean

For convenience, the useMomentaryBool hook has been included to momentarily toggle a boolean. This wraps the useDelay hook.

This is very useful for momentary notifications, such as a copy button that shows a momentary checkmark to indicate the operation succeeded.

import { useMomentaryBool } from 'react-use-precision-timer';

In your function component:

// Toggle to true, then back to false after 1000ms.
const [value, toggle] = useMomentaryBool(false, 1000);

Calling toggle() will set the boolean to true, then back to false after a 1000 millisecond delay.

Other Usage

See useTimer for all other hook options and timer functions.

Timer Renderer

This timer hook operates entirely on Unix timestamps and timeouts. If it's being used as a stopwatch, no timeouts are used at all.

This means there isn't a separate render timer running to render the timer's state to the page. So it may appear as if your timer or stopwatch isn't running, but that's not the case—you're just not telling React to render it to the page!

To solve this, you can render a timer or stopwatch to the page as it runs with the TimerRenderer component. Use it like so:

import { TimerRenderer } from 'react-use-precision-timer';
const myTimer = useTimer(...); // Or useStopwatch()
  render={(t) => <>{t.getElapsedRunningTime()}</>}
  renderRate={10} // In milliseconds

Provide a render prop function that takes one argument, the timer. The render function should return your rendered timer or stopwatch.

The renderRate prop determines how frequently the component renders, in milliseconds. If no renderRate is provided, the default is 10 milliseconds.


Type definitions have been included for TypeScript support.

Icon Attribution

Favicon by Twemoji.


Open source software is awesome and so are you. 😎

Feel free to submit a pull request for bugs or additions, and make sure to update tests as appropriate. If you find a mistake in the docs, send a PR! Even the smallest changes help.

For major changes, open an issue first to discuss what you'd like to change.

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