react-native-countup

Customizable react native component for number animations.

• Examples
• Basic
• Formatting
• Timing function
• Counting
• Props

Installation

$ npm install react-native-countup

Usage

import AnimateNumber from 'react-native-countup'

Examples

Basic

The only required property is value, when this property changes, it automatically interpolates value and performs animation.

<AnimateNumber value={100}/>

You can also pass in an initial value to interpolate from:

<AnimateNumber initial={50} value={100}/>

Formatting

You can customize text format by specifying formatter prop, this property must be a function.

<AnimateNumber value={100} formatter={(val) => {
    return '$ ' + parseFloat(val).toFixed(2)
  }}/>

Timing function

There're 3 built-in timing functions which are linear, easeIn, and easeOut. It is also possible customize your timing function, see examples bellow.

Built-in timing function

<AnimateNumber value={100} timing="linear"/>
<AnimateNumber value={100} timing="easeOut"/>
<AnimateNumber value={100} timing="easeIn"/>

Customized timing function

Customized timing function returns a number which represents the length of animation frame.

interval

Basic interval length of animation frame, default value is 14 ms. You can change this value by interval prop.

progress

A float number between 0 to 1, which means the progress of animation.

<AnimateNumber value={200}
  countBy={1}
  timing={(interval, progress) => {
    // slow start, slow end
    return interval * (1 - Math.sin(Math.PI*progress) )*10
  }}/>

Counting

By default this component calculates value increment of each animation frame, but you can customize this rule by set prop countBy.

<AnimateNumber value={100} countBy={1} />

But keep in mind if the countBy value is relative small than value, the animation may persists for a very long time. Like the following example, it will tasks 150 seconds to finish the animation.

<AnimateNumber value={10000} interval={15} countBy={1} />

Props

value:number(required)

The value of AnimateNumber component.

countBy:number(optional default to null)

Set this property to force the component's value increase/decrease by this number.

interval:number(optional default to 14)

Base interval of each animation frame, in ms.

steps:number(optional default to 45)

Set total frame number of animation, say, if interval is 14 and steps is 30, the animation will take 14x30ms to finish when it uses linear timing function.

timing: 'linear' | 'easeOut' | 'easeIn' | () => number

Custom timing function or use a default timing function.

formatter: () => string(optional)

This prop accepts a function which returns a string as displayed value.

onProgress: () => void(optional)

A function that triggers when text state has updated.

onFinish: () => void(optional)

A function that triggers when animation completes.