---

Key features

:trophy: Lighter implementation and smaller bundle size in comparison with similar feature solutions
:flags: Declarative API _(no more imperative calls to start() and update())_
 :iphone:  React Native support for iOS and Android
:deciduous_tree: Tree-shakable
 :file_cabinet: Server-side rendering (SSR) compatibility

Installation

``
yarn add use-count-up
`

Demo

Check the React demo on CodeSandbox and React Native demo on Expo Snack to get started.

Component basic usage

`jsx
import { CountUp } from 'use-count-up'

const MyComponent = () =>
`

The CountUp component should be wrapped in a Text component when used in a React Native project like so:

`jsx
import { Text } from 'react-native'
import { CountUp } from 'use-count-up'

const MyComponent = () => (



)
`

Hook basic usage

The hook accepts the same properties as the component. The usage for React and React Native is the same.

`jsx
import { useCountUp } from 'use-count-up'

const MyComponent = () => {
const { value } = useCountUp({
isCounting: true,
end: 1320,
duration: 3.2,
})

return value
}
`

Props

The component and the hook accept the same props. They are fully interchangeable.

| Prop Name | Type | Default | Description |
| ---------------------- | ------------------ | ------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| isCounting | boolean | false | Play and pause counting animation |
| start | number | 0 | Initial value |
| end | number | - | Target value |
| duration | number | - | Animation duration in seconds. Defaults to 2 seconds if end is set |
| decimalPlaces | number | - | Number of decimal places after the decimal separator. Defaults to the max decimal places count from start and end props |
| decimalSeparator | string | - | Decimal separator character |
| thousandsSeparator | string | - | Thousands separator character |
| easing | string \| function | easeOutCubic | _Type: easeOutCubic \| easeInCubic \| linear \| easing func_
Easing function to control the animation progress |
| formatter | function | - | _Type: (value: number) => number \| string \| node_
A function that formats the output value. It has the highest priority so all other formatting options are ignored |
| updateInterval | number | 0 | Update interval in seconds. Determines how often the animated value will change. When set to 0 the value will update on each key frame |
| children | function | - | _Type: ({ value: number, reset: () => void }) => number \| string \| node_
CountUp component - children prop |
| onComplete | function | - | _Type: () => void \| {shouldRepeat: boolean, delay: number}_
On complete handler. Repeat animation by returning an object with shouldRepeat equals true and delay in seconds. |
| onUpdate | function | - | _Type: (currentValue: number \| string \| node) => void_
On value update event handler |

Return values

The hook returns the current count up value and reset method to reset the animation.

`jsx
import { useCountUp } from 'use-count-up'

const { value, reset } = useCountUp({ isCounting: true })
`

The component's children render function will receive as props the current count up value and reset method to reset the animation.

`jsx
import { CountUp } from 'use-count-up'

const MyComponent = () => (
{({ value, reset }) => value}
)
`



Why use toLocaleString with formatter



Number formatting varies per language group. For example, the number 3842.45 in German will be formatted as 3.842,45 whereas in British English it will be 3,842.45 (spot the different decimal and thousands separators). Number.toLocaleString() is a built-in JS method that returns a string with a language-sensitive representation of the number. The basic implementation of the method will detect the default locale that is set up on the user's computer and will format the number accordingly. The browser support for toLocaleString is incredibly good.

If you expect variance in the geographical/country distribution of your users, then this is a must. The simplest way to use toLocaleString with the Count up component or hook is to use the formatter prop, like so:

`jsx
import { CountUp } from 'use-count-up'

const MyComponent = () => (
isCounting
end={1320}
formatter={(value) => value.toLocaleString()}
/>
)
`

toLocaleString method accepts an object with two parameters, locale and options, which allows further customization of the number value. Setting up the first parameter, locale, allows the use of a specific locale and fallback option. The second parameter, options, will let you format the value in a custom way. For example, you may choose to add a min and max number of decimal places, or set currency. Keep in mind though that the locale and options arguments are not supported in all browsers.

Recipes

$3

Pass a key prop to CountUp component and change it when the animation should repeat. It can be also used when a change of start or end value should start the animation over.

`jsx
import { CountUp } from 'use-count-up'

const MyComponent = ({ end }) =>
`

$3

Return from the onComplete handler an object with key shouldRepeat: true. Optionally the delay before repeating can be set. In the example below the animation will be repeated in 2 seconds

`jsx
import { CountUp } from 'use-count-up'

const onComplete = () => {
// do your stuff here
return { shouldRepeat: true, delay: 2 }
}

const MyComponent = () => (

)
`

$3

Don't provide end and duration props. start prop can be set to any value

`jsx
import { CountUp } from 'use-count-up'

const MyComponent = () =>
`

$3

Set the easing to "linear" and duration to the seconds it should count up/down. The updateInterval can be set to 1, so it updates once every second. Here is an example of a 10-second count-down:

`jsx
import { CountUp } from 'use-count-up'

const MyComponent = () => (
isCounting
start={10}
end={0}
duration={10}
easing="linear"
updateInterval={1}
onUpdate={(currentValue) => {
// it will fire once every second
}}
/>
)
``