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30-seconds-of-code/snippets/Collapse.md
Angelos Chalaris 2a28e1dff1 Resolve #53
2019-03-06 20:46:04 +02:00

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### Collapse
Renders a component with collapsible content.
* Use the `React.setState()` hook to create the `isCollapsed` state variable with an initial value of `props.collapsed`.
* Use an object, `style`, to hold the styles for individual components and their states.
* Use a `<div>` to wrap both the `<button>` that alters the component's `isCollapsed` state and the content of the component, passed down via `props.children`.
* Determine the appearance of the content, based on `isCollapsed` and apply the appropriate CSS rules from the `style` object.
* Finally, update the value of the `aria-expanded` attribute based on `isCollapsed` to make the component accessible.
```jsx
function Collapse(props) {
const [isCollapsed, setIsCollapsed] = React.useState(props.collapsed);
const style = {
collapsed: {
display: 'none'
},
expanded: {
display: 'block'
},
buttonStyle: {
display: 'block',
width: '100%'
}
};
return (
<div>
<button style={style.buttonStyle} onClick={() => setIsCollapsed(!isCollapsed)}>
{isCollapsed ? 'Show' : 'Hide'} content
</button>
<div
className="collapse-content"
style={isCollapsed ? style.collapsed : style.expanded}
aria-expanded={isCollapsed}
>
{props.children}
</div>
</div>
);
}
```
```jsx
ReactDOM.render(
<Collapse>
<h1>This is a collapse</h1>
<p>Hello world!</p>
</Collapse>,
document.getElementById('root')
);
```
<!-- tags: visual,children,state -->
<!-- expertise: 2 -->