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30-seconds-of-code/snippets/Collapse.md

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### Collapse
Renders a component with collapsible content.
Use the value of the `collapsed` prop to determine the initial state of the content (collapsed/expanded).
Set the `state` of the component to the value of the `collapsed` prop (cast to a boolean value) and bind the `toggleCollapse` method to the component's context.
Use an object, `style`, to hold the styles for individual components and their states.
Create a method, `toggleCollapse` to change the component's `state` from collapsed to expanded and vice versa.
In the `render()` method, use a `<div>` to wrap both the `<button>` that alters the component's `state` and the content of the component, passed down via `props.children`.
Determine the appearance of the content, based on `state.collapsed` and apply the appropriate CSS rules from the `style` object.
Finally, update the value of the `aria-expanded` attribute based on `state.collapsed` to make the component accessible.
```jsx
const style = {
collapsed: {
display: "none"
},
expanded: {
display: "block"
},
buttonStyle: {
display: "block",
width: "100%"
}
};
function Collapse(props) {
const [isCollapsed, setCollapsed] = useState(props.collapsed);
const toggleCollapse = () => {
setCollapsed(!isCollapsed);
};
return (
<div>
<button style={style.buttonStyle} onClick={() => toggleCollapse()}>
{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,class -->
<!-- expertise: 2 -->