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30-seconds-of-code/snippets/Collapse.md
Angelos Chalaris bc9bbacad3 Update tags
2019-02-12 22:07:13 +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 -->