Files F102000033

focustrap.js
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Created: Sun, Feb 16, 01:09

focustrap.js
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	/**
	* --------------------------------------------------------------------------
	* Bootstrap (v5.2.3): util/focustrap.js
	* Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
	* --------------------------------------------------------------------------
	*/

	import EventHandler from '../dom/event-handler'
	import SelectorEngine from '../dom/selector-engine'
	import Config from './config'

	/**
	* Constants
	*/

	const NAME = 'focustrap'
	const DATA_KEY = 'bs.focustrap'
	const EVENT_KEY = `.${DATA_KEY}`
	const EVENT_FOCUSIN = `focusin${EVENT_KEY}`
	const EVENT_KEYDOWN_TAB = `keydown.tab${EVENT_KEY}`

	const TAB_KEY = 'Tab'
	const TAB_NAV_FORWARD = 'forward'
	const TAB_NAV_BACKWARD = 'backward'

	const Default = {
	autofocus: true,
	trapElement: null // The element to trap focus inside of
	}

	const DefaultType = {
	autofocus: 'boolean',
	trapElement: 'element'
	}

	/**
	* Class definition
	*/

	class FocusTrap extends Config {
	constructor(config) {
	super()
	this._config = this._getConfig(config)
	this._isActive = false
	this._lastTabNavDirection = null
	}

	// Getters
	static get Default() {
	return Default
	}

	static get DefaultType() {
	return DefaultType
	}

	static get NAME() {
	return NAME
	}

	// Public
	activate() {
	if (this._isActive) {
	return
	}

	if (this._config.autofocus) {
	this._config.trapElement.focus()
	}

	EventHandler.off(document, EVENT_KEY) // guard against infinite focus loop
	EventHandler.on(document, EVENT_FOCUSIN, event => this._handleFocusin(event))
	EventHandler.on(document, EVENT_KEYDOWN_TAB, event => this._handleKeydown(event))

	this._isActive = true
	}

	deactivate() {
	if (!this._isActive) {
	return
	}

	this._isActive = false
	EventHandler.off(document, EVENT_KEY)
	}

	// Private
	_handleFocusin(event) {
	const { trapElement } = this._config

	if (event.target === document \|\| event.target === trapElement \|\| trapElement.contains(event.target)) {
	return
	}

	const elements = SelectorEngine.focusableChildren(trapElement)

	if (elements.length === 0) {
	trapElement.focus()
	} else if (this._lastTabNavDirection === TAB_NAV_BACKWARD) {
	elements[elements.length - 1].focus()
	} else {
	elements[0].focus()
	}
	}

	_handleKeydown(event) {
	if (event.key !== TAB_KEY) {
	return
	}

	this._lastTabNavDirection = event.shiftKey ? TAB_NAV_BACKWARD : TAB_NAV_FORWARD
	}
	}

	export default FocusTrap

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