# focus-trap

 > Add focus traps around elements.

Adding a focus traps is important part of making your site accessible. The most common example where you want to set up a focus trap is a modal. While modal is open, the user shouldn't be able to tab outside of it, and focus should be locked within the modal elements. You have to remember to make sure there is always a way how to exit this focus trap. In modal example it's usually the escape key, or close button in the corner.

 [Demo](https://codesandbox.io/s/4rn8vm4nv0)

## Install

Using npm
```sh
npm install @daniel.husar/focus-trap
```

Using yarn
```sh
yarn add @daniel.husar/focus-trap
```

## Usage

```javascript
import FocusTrap from '@daniel.husar/focus-trap';
// Setup trap
const trap = new FocusTrap({ node: document.querySelector('#my-trap') });
// Release trap
trap.restore();
```

### Constructor API
Constructor accept object with those properties:

```javascript
new FocusTrap({
  node: document.querySelector('#my-trap') }),
  firstElement: () => document.querySelector('#first-element'),
  lastElement: () => document.querySelector('#last-element'),
  disableStartingTrap: () => false,
  disableEndingTrap: () => false,
});
```

#### node

Type: `DOM element`

Default: `none`

Required: `true`

This is the DOM node you want to set-up focus trap around

#### firstElement

Type: `Function`

Default: `() => null`

Required: `none`

Function that returns element that will replace first element when focus will jump back at the start. Usefull when you want to connect 2 focus traps together. Will fallback to firstElement in focus trap if function returns falsy value.

#### lastElement

Type: `Function`

Default: `() => null`

Required: `none`

Function that returns element that will replace last element when focus will jump back at the end. Usefull when you want to connect 2 focus traps together. Will fallback to lastElement in focus trap if function returns falsy value.

#### disableStartingTrap

Type: `Function`

Default: `() => false`

Required: `none`

Function that returns boolean if the starting trap should be disabled.

#### disableEndingTrap

Type: `Function`

Default: `() => false`

Required: `none`

Function that can returns boolean if the ending trap should be disabled.

### Interface

#### recalculateFocusableElements

Type: `Function`

Recalculate focusable elements inside of your trap. Usefull if content of the node changes over time.

#### restore

Type: `Function`

Remove the focus trap from element.

## License

MIT © [Daniel Husar](https://github.com/danielhusar)