A customizable countdown component for React.
You can install the module via npm or yarn:
npm install react-countdown --saveyarn add react-countdownAs part of a small web app at first, the idea was to separate the countdown component from the main package to combine general aspects of the development with React, testing with Jest and more things that relate to publishing a new Open Source project.
Here are some examples which you can try directly online. You can also clone this repo and explore some more examples in there by running yarn start within the examples folder.
A very simple and minimal example of how to set up a countdown that counts down from 10 seconds.
import React from 'react';
import ReactDOM from 'react-dom';
import Countdown from 'react-countdown';
ReactDOM.render(
<Countdown date={Date.now() + 10000} />,
document.getElementById('root')
);In case you want to change the output of the component or want to signal that the countdown's work is done, you can do this by either using the onComplete callback, a
custom renderer, or by specifying a React child within <Countdown></Countdown>, which will only be shown once the countdown is complete.
import React from 'react';
import ReactDOM from 'react-dom';
import Countdown from 'react-countdown';
// Random component
const Completionist = () => <span>You are good to go!</span>;
ReactDOM.render(
(
<Countdown date={Date.now() + 5000}>
<Completionist />
</Countdown>
),
document.getElementById('root')
);import React from 'react';
import ReactDOM from 'react-dom';
import Countdown from 'react-countdown';
// Random component
const Completionist = () => <span>You are good to go!</span>;
// Renderer callback with condition
const renderer = ({ hours, minutes, seconds, completed }) => {
if (completed) {
// Render a completed state
return <Completionist />;
} else {
// Render a countdown
return <span>{hours}:{minutes}:{seconds}</span>;
}
};
ReactDOM.render(
<Countdown
date={Date.now() + 5000}
renderer={renderer}
/>,
document.getElementById('root')
);Here is an example with a countdown of 10 seconds that displays the total time difference in milliseconds. In order to display the milliseconds appropriately, the intervalDelay value needs to be lower than 1000ms and a precision of 1 to 3 should be used. Last but not least, a simple renderer callback needs to be set up.
import React from 'react';
import ReactDOM from 'react-dom';
import Countdown from 'react-countdown';
ReactDOM.render(
<Countdown
date={Date.now() + 10000}
intervalDelay={0}
precision={3}
renderer={props => <div>{props.total}</div>}
/>,
document.getElementById('root')
);| Name | Type | Default | Description |
|---|---|---|---|
| date | Date|string|number |
required | Date or timestamp in the future |
| key | string|number |
undefined |
React key; can be used to restart the countdown |
| daysInHours | boolean |
false |
Days are calculated as hours |
| zeroPadTime | number |
2 |
Length of zero-padded output, e.g.: 00:01:02 |
| zeroPadDays | number |
zeroPadTime |
Length of zero-padded days output, e.g.: 01 |
| controlled | boolean |
false |
Hands over the control to its parent(s) |
| intervalDelay | number |
1000 |
Interval delay in milliseconds |
| precision | number |
0 |
The precision on a millisecond basis |
| autoStart | boolean |
true |
Countdown auto-start option |
| overtime | boolean |
false |
Counts down to infinity |
| children | any |
null |
A React child for the countdown's completed state |
| renderer | function |
undefined |
Custom renderer callback |
| now | function |
Date.now |
Alternative handler for the current date |
| onMount | function |
undefined |
Callback when component mounts |
| onStart | function |
undefined |
Callback when countdown starts |
| onPause | function |
undefined |
Callback when countdown pauses |
| onStop | function |
undefined |
Callback when countdown stops |
| onTick | function |
undefined |
Callback on every interval tick (controlled = false) |
| onComplete | function |
undefined |
Callback when countdown ends |
The date prop is the only required one and can be a Date object, string, or timestamp in the future. By default, this date is compared with the current date, or a custom handler defined via now.
Valid values can be (and more):
'2020-02-01T01:02:03'//Datetime string format1580518923000// Timestamp in millisecondsnew Date(1580518923000)//Dateobject
This is one of React's internal component props to help identify elements throughout the reconciliation process. It can be used to restart the countdown by
passing in a new string or number value.
Please see official React docs for more information about keys.
Defines whether the time of day should be calculated as hours rather than separated days.
Can be useful if the countdown's interval and/or date control should be handed over to the parent. In case controlled is true, the
provided date will be treated as the countdown's actual time difference and not be compared to now anymore.
This option defaults to 2 in order to display the common format 00:00:00 instead of 0:0:0. If the value is higher than 2, only the hours part (see zeroPadDays for days) will be zero-padded while it stays at 2 for minutes as well as seconds. If the value is lower, the output won't be zero-padded like the example before is showing.
Defaults to zeroPadTime. It works the same way as zeroPadTime does, just for days.
Since this countdown is based on date comparisons, the default value of 1000 milliseconds is probably enough for most scenarios and doesn't need to be changed.
However, if it needs to be more precise, the intervalDelay can be set to something lower - down to 0, which would, for example, allow showing the milliseconds in a more fancy way (currently only possible through a custom renderer).
In certain cases, you might want to base off the calculations on a millisecond basis. The precision prop, which defaults to 0, can be used to refine this calculation. While the default value simply strips the milliseconds part (e.g., 10123ms => 10000ms), a precision of 3 leads to 10123ms.
Defines whether the countdown should start automatically or not. Defaults to true.
Defines whether the countdown can go into overtime by extending its lifetime past the targeted endpoint. Defaults to false.
When set to true, the countdown timer won't stop when hitting 0, but instead becomes negative and continues to run unless paused/stopped. The onComplete callback would still get triggered when the initial countdown phase completes.
Please note that the
childrenprop will be ignored ifovertimeistrue. Also, when using a customrenderer, you'll have to check one of the render props, e.g.,total, orcompleted, to render the overtime output.
This component also considers the child that may live within the <Countdown></Countdown> element, which, in case it's available, replaces the countdown's component state once it's complete. Moreover, an additional prop called countdown is set and contains data similar to what the renderer callback would receive. Here's an example that showcases its usage.
Please note that the
childrenprop will be ignored if a customrendereris defined.
The component's raw render output is kept very simple.
For more advanced countdown displays, a custom renderer callback can be defined to return a new React element. It receives the following render props as the first argument.
The render props object consists of the current time delta object, the countdown's api, the component props, and last but not least, a formatted object.
{
total: 0,
days: 0,
hours: 0,
minutes: 0,
seconds: 0,
milliseconds: 0,
completed: true,
api: { ... },
props: { ... },
formatted: { ... }
}Please note that a defined custom
rendererwill ignore thechildrenprop.
If the current date and time (determined via a reference to Date.now) is not the right thing to compare with for you, a reference to a custom function that returns a similar dynamic value could be provided as an alternative.
onMount is a callback and triggered when the countdown mounts. It receives a time delta object as the first argument.
onStart is a callback and triggered whenever the countdown is started (including first-run). It receives a time delta object as the first argument.
onPause is a callback and triggered every time the countdown is paused. It receives a time delta object as the first argument.
onStop is a callback and triggered every time the countdown is stopped. It receives a time delta object as the first argument.
onTick is a callback and triggered every time a new period is started, based on what the intervalDelay's value is. It only gets triggered when the countdown's controlled prop is set to false, meaning that the countdown has full control over its interval. It receives a time delta object as the first argument.
onComplete is a callback and triggered whenever the countdown ends. In contrast to onTick, the onComplete callback also gets triggered in case controlled is set to true. It receives a time delta object as the first argument and a boolean as a second argument, indicating whether the countdown transitioned into the completed state (false) or completed on start (true).
The countdown component exposes a simple API through the getApi() function that can be accessed via component ref. It is also part (api) of the render props passed into renderer if needed. Here's an example of how to use it.
Starts the countdown in case it is paused/stopped or needed when autoStart is set to false.
Pauses the running countdown. This only works as expected if the controlled prop is set to false because calcTimeDelta calculates an offset time internally.
Stops the countdown. This only works as expected if the controlled prop is set to false because calcTimeDelta calculates an offset time internally.
Returns a boolean for whether the countdown has been paused or not.
Returns a boolean for whether the countdown has been stopped or not.
Returns a boolean for whether the countdown has been completed or not.
Please note that this will always return
falseifovertimeistrue. Nevertheless, an into overtime running countdown's completed state can still be looking at the time delta object'scompletedvalue.
This module also exports three simple helper functions, which can be utilized to build your own countdown custom renderer.
import Countdown, { zeroPad, calcTimeDelta, formatTimeDelta } from 'react-countdown';The zeroPad function transforms and returns a given value with padded zeros depending on the length. The value can be a string or number, while the length parameter can be a number, defaulting to 2. Returns the zero-padded string, e.g., zeroPad(5) => 05.
const renderer = ({ hours, minutes, seconds }) => (
<span>
{zeroPad(hours)}:{zeroPad(minutes)}:{zeroPad(seconds)}
</span>
);calcTimeDelta calculates the time difference between a given end date and the current date (now). It returns, similar to the renderer callback, a custom object (also referred to as countdown time delta object) with the following time-related data:
{ total, days, hours, minutes, seconds, milliseconds, completed }The total value is the absolute time difference in milliseconds, whereas the other time-related values contain their relative portion of the current time difference. The completed value signalizes whether the countdown reached its initial end or not.
The calcTimeDelta function accepts two arguments in total; only the first one is required.
date
Date or timestamp representation of the end date. See date prop for more details.
options The second argument consists of the following optional keys.
-
now = Date.nowAlternative function for returning the current date, also seenow. -
precision = 0Theprecisionon a millisecond basis. -
controlled = falseDefines whether the calculated value is provided in acontrolledenvironment as the time difference or not. -
offsetTime = 0Defines the offset time that gets added to the start time; only considered if controlled is false. -
overtime = falseDefines whether the time delta can go intoovertimeand become negative or not. When set totrue, thetotalcould become negative, at which pointcompletedwill still be set totrue.
formatTimeDelta formats a given countdown time delta object. It returns the formatted portion of it, equivalent to:
{
days: '00',
hours: '00',
minutes: '00',
seconds: '00',
}This function accepts two arguments in total; only the first one is required.
timeDelta
Time delta object, e.g., returned by calcTimeDelta.
options
The options object consists of the following three component props and is used to customize the time delta object's formatting:
A common reason for this is that the date prop gets passed directly into the component without persisting it in any way.
In order to avoid this from happening, it should be stored in a place that persists throughout lifecycle changes, for example, in the component's local state.
Why aren't my values formatted when using the custom renderer?
The renderer callback gets called with a time delta object that also consists of a formatted object which holds these formatted values.
This could have something to do with server-side rendering and that the countdown already runs on the server-side, resulting in a timestamp discrepancy between the client and the server. In this case, it might be worth checking https://reactjs.org/docs/dom-elements.html#suppresshydrationwarning.
Alternatively, you could try to set autoStart to false and start the countdown through the API once it's available on the client. Here are some related issues that might help in fixing this problem.
Contributions of any kind are very welcome. Read more in our contributing guide about how to report bugs, create pull requests, and other development-related topics.
MIT