# React Animate Height [![npm version](https://img.shields.io/npm/v/react-animate-height.svg?style=flat-square)](https://www.npmjs.com/package/react-animate-height) [![npm downloads](https://img.shields.io/npm/dm/react-animate-height.svg?style=flat-square)](https://www.npmjs.com/package/react-animate-height) Lightweight React component for animating height using CSS transitions. Slide an element up and down or animate it to any specific height. Content's opacity can be optionally animated as well (check `animateOpacity` prop bellow). CSS classes are applied in specific animation states, check `animationStateClasses` prop. [Changelog](CHANGELOG.md) ### Note about versions For React >=16.3.0 make sure you are using v2.x. Read more about [React lifecycle changes](https://reactjs.org/blog/2018/03/27/update-on-async-rendering.html) introduced with React 16.3. ## Demo Live demo: [muffinman.io/react-animate-height](https://muffinman.io/react-animate-height/) Because multiple people asked how to animate list items, I created this [simple example](https://codesandbox.io/s/react-animated-list-example-made-using-react-animate-height-je9q1) for that as well. To build the examples locally, run: ``` npm install npm start ``` Then open [`localhost:8080`](http://localhost:8080) in your browser of choice browser. Or play with this [sandbox](https://codesandbox.io/s/react-animate-height-basic-example-ql384). ## Quick start Get it from npm ``` $ npm install --save react-animate-height ``` Import and use it in your React app. ```jsx import React, { Component } from 'react'; import AnimateHeight from 'react-animate-height'; export default class Example extends Component { state = { height: 0, }; toggle = () => { const { height } = this.state; this.setState({ height: height === 0 ? 'auto' : 0, }); }; render() { const { height } = this.state; return (

Your content goes here

Put as many React or HTML components here.
); } } ``` ### Props * **height**: numeric or percentage value (ie. `'50%'`) or `'auto'`, required When changed, element height will be animated to that height.
To slide up use 0, for slide down use 'auto' * **duration**: integer, default: `250` Duration of the animation in milliseconds * **delay**: integer, default: `0` Animation delay in milliseconds * **easing**: string, default: `'ease'` CSS easing function to be applied to the animation * **id**: string HTML `id` attribute. * **className**: string CSS class to be applied to the element **Please note that you shouldn't apply properties that are messing with the layout (like `display`, `height`...), as these might break height calculations** * **style**: object CSS style object, it will be merged with inline styles of the component **Please note that you shouldn't apply properties that are messing with the layout (like `display`, `height`...), as these might break height calculations** * **contentClassName**: string CSS class to be applied to content wrapper element **Please note that you shouldn't apply properties that are messing with the layout (like `display`, `height`...), as these might break height calculations** * **animationStateClasses**: object Object containing CSS class names for animation states, default: ``` { animating: 'rah-animating', animatingUp: 'rah-animating--up', animatingDown: 'rah-animating--down', static: 'rah-static', animatingToHeightZero: 'rah-animating--to-height-zero', animatingToHeightAuto: 'rah-animating--to-height-auto', animatingToHeightSpecific: 'rah-animating--to-height-specific', staticHeightZero: 'rah-static--height-zero', staticHeightAuto: 'rah-static--height-auto', staticHeightSpecific: 'rah-static--height-specific', } ``` Please note that this one will be merged with the default object and cached when component is created, so changing it afterwards will have no effect. * **onAnimationStart**: function Callback which will be called when animation starts. This first argument passed to this callback is an object containing `newHeight`, the pixel value of the height at which the animation will end. * **onAnimationEnd**: function Callback which will be called when animation ends. This first argument passed to this callback is an object containing `newHeight`, the pixel value of the height at which the animation ended. * **applyInlineTransitions**: boolean, default: `true` If this flag is set to `false` only CSS classes will be applied to the element and inline transition styles will not be present. * **animateOpacity**: boolean, default: `false` If set to `true` content will fade-in (and fade-out) while height is animated. * **aria-hidden**: boolean By default, library will set `aria-hidden` to `true` when height is zero. If you wish to override it, you can pass the prop yourself. Additional props will be passed to the wrapper div, to make adding attrs like `aria-*` easier. ## Accessibility Library will hide the content using `display: hidden` when height props is 0. It will also apply `aria-hidden="true"` in the same case, but you can override it by passing `aria-hidden` prop yourself. When using a button to toggle height, make sure you add `aria-expanded` and `aria-controls` to make everything accessible. Here's an example: ```jsx Content ``` ### Reduced motion Component checks for `prefers-reduced-motion` in the constructor and disables animations if it set to true. Please note that component doesn't listen for potential changes of `prefers-reduced-motion` option. ## Gotchas ### Bounded flexboxes If `AnimateHeight` is a flex child and it's parent has a fixed height, animation won't work. To fix this, you just need to add the following CSS rule to the `AnimateHeight` instance. ```css flex-shrink: 0; ``` You can do it by passing a `className` or directly in the `style` prop ```jsx ``` Check the [issue #89](https://github.com/Stanko/react-animate-height/issues/89) for the example and more details. ## License [MIT](https://github.com/Stanko/react-animate-height/blob/master/LICENSE)