{"version":3,"file":"focus-visible.min.js","sources":["../src/focus-visible.js"],"sourcesContent":["/**\n * https://github.com/WICG/focus-visible\n */\nfunction init() {\n  var hadKeyboardEvent = true;\n  var hadFocusVisibleRecently = false;\n  var hadFocusVisibleRecentlyTimeout = null;\n\n  var inputTypesWhitelist = {\n    text: true,\n    search: true,\n    url: true,\n    tel: true,\n    email: true,\n    password: true,\n    number: true,\n    date: true,\n    month: true,\n    week: true,\n    time: true,\n    datetime: true,\n    'datetime-local': true\n  };\n\n  /**\n   * Helper function for legacy browsers and iframes which sometimes focus\n   * elements like document, body, and non-interactive SVG.\n   * @param {Element} el\n   */\n  function isValidFocusTarget(el) {\n    if (\n      el &&\n      el !== document &&\n      el.nodeName !== 'HTML' &&\n      el.nodeName !== 'BODY' &&\n      'classList' in el &&\n      'contains' in el.classList\n    ) {\n      return true;\n    }\n    return false;\n  }\n\n  /**\n   * Computes whether the given element should automatically trigger the\n   * `focus-visible` class being added, i.e. whether it should always match\n   * `:focus-visible` when focused.\n   * @param {Element} el\n   * @return {boolean}\n   */\n  function focusTriggersKeyboardModality(el) {\n    var type = el.type;\n    var tagName = el.tagName;\n\n    if (tagName == 'INPUT' && inputTypesWhitelist[type] && !el.readOnly) {\n      return true;\n    }\n\n    if (tagName == 'TEXTAREA' && !el.readOnly) {\n      return true;\n    }\n\n    if (el.isContentEditable) {\n      return true;\n    }\n\n    return false;\n  }\n\n  /**\n   * Add the `focus-visible` class to the given element if it was not added by\n   * the author.\n   * @param {Element} el\n   */\n  function addFocusVisibleClass(el) {\n    if (el.classList.contains('focus-visible')) {\n      return;\n    }\n    el.classList.add('focus-visible');\n    el.setAttribute('data-focus-visible-added', '');\n  }\n\n  /**\n   * Remove the `focus-visible` class from the given element if it was not\n   * originally added by the author.\n   * @param {Element} el\n   */\n  function removeFocusVisibleClass(el) {\n    if (!el.hasAttribute('data-focus-visible-added')) {\n      return;\n    }\n    el.classList.remove('focus-visible');\n    el.removeAttribute('data-focus-visible-added');\n  }\n\n  /**\n   * Treat `keydown` as a signal that the user is in keyboard modality.\n   * Apply `focus-visible` to any current active element and keep track\n   * of our keyboard modality state with `hadKeyboardEvent`.\n   * @param {Event} e\n   */\n  function onKeyDown(e) {\n    if (isValidFocusTarget(document.activeElement)) {\n      addFocusVisibleClass(document.activeElement);\n    }\n\n    hadKeyboardEvent = true;\n  }\n\n  /**\n   * If at any point a user clicks with a pointing device, ensure that we change\n   * the modality away from keyboard.\n   * This avoids the situation where a user presses a key on an already focused\n   * element, and then clicks on a different element, focusing it with a\n   * pointing device, while we still think we're in keyboard modality.\n   * @param {Event} e\n   */\n  function onPointerDown(e) {\n    hadKeyboardEvent = false;\n  }\n\n  /**\n   * On `focus`, add the `focus-visible` class to the target if:\n   * - the target received focus as a result of keyboard navigation, or\n   * - the event target is an element that will likely require interaction\n   *   via the keyboard (e.g. a text box)\n   * @param {Event} e\n   */\n  function onFocus(e) {\n    // Prevent IE from focusing the document or HTML element.\n    if (!isValidFocusTarget(e.target)) {\n      return;\n    }\n\n    if (hadKeyboardEvent || focusTriggersKeyboardModality(e.target)) {\n      addFocusVisibleClass(e.target);\n    }\n  }\n\n  /**\n   * On `blur`, remove the `focus-visible` class from the target.\n   * @param {Event} e\n   */\n  function onBlur(e) {\n    if 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{\n      // If the tab becomes active again, the browser will handle calling focus\n      // on the element (Safari actually calls it twice).\n      // If this tab change caused a blur on an element with focus-visible,\n      // re-apply the class when the user switches back to the tab.\n      if (hadFocusVisibleRecently) {\n        hadKeyboardEvent = true;\n      }\n      addInitialPointerMoveListeners();\n    }\n  }\n\n  /**\n   * Add a group of listeners to detect usage of any pointing devices.\n   * These listeners will be added when the polyfill first loads, and anytime\n   * the window is blurred, so that they are active when the window regains\n   * focus.\n   */\n  function addInitialPointerMoveListeners() {\n    document.addEventListener('mousemove', onInitialPointerMove);\n    document.addEventListener('mousedown', onInitialPointerMove);\n    document.addEventListener('mouseup', onInitialPointerMove);\n    document.addEventListener('pointermove', onInitialPointerMove);\n    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onInitialPointerMove);\n  }\n\n  /**\n   * When the polfyill first loads, assume the user is in keyboard modality.\n   * If any event is received from a pointing device (e.g. mouse, pointer,\n   * touch), turn off keyboard modality.\n   * This accounts for situations where focus enters the page from the URL bar.\n   * @param {Event} e\n   */\n  function onInitialPointerMove(e) {\n    // Work around a Safari quirk that fires a mousemove on <html> whenever the\n    // window blurs, even if you're tabbing out of the page. ¯\\_(ツ)_/¯\n    if (e.target.nodeName.toLowerCase() === 'html') {\n      return;\n    }\n\n    hadKeyboardEvent = false;\n    removeInitialPointerMoveListeners();\n  }\n\n  document.addEventListener('keydown', onKeyDown, true);\n  document.addEventListener('mousedown', onPointerDown, true);\n  document.addEventListener('pointerdown', onPointerDown, true);\n  document.addEventListener('touchstart', onPointerDown, true);\n  document.addEventListener('focus', onFocus, 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