Adding upstream version 5.2.3+dfsg.

Signed-off-by: Daniel Baumann <daniel@debian.org>

js/src/util/focustrap.js

@@ -0,0 +1,115 @@
+/**
+ * --------------------------------------------------------------------------
+ * 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