119 lines
5.3 KiB
JavaScript
119 lines
5.3 KiB
JavaScript
import $ from 'jquery';
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let ariaIdCounter = 0;
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function generateAriaId() {
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return `_aria_auto_id_${ariaIdCounter++}`;
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}
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// make the item has role=option, and add an id if there wasn't one yet.
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function prepareMenuItem($item) {
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if (!$item.attr('id')) $item.attr('id', generateAriaId());
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$item.attr({'role': 'menuitem', 'tabindex': '-1'});
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$item.find('a').attr('tabindex', '-1'); // as above, the elements inside the dropdown menu item should not be focusable, the focus should always be on the dropdown primary element.
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}
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// when the menu items are loaded from AJAX requests, the items are created dynamically
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const defaultCreateDynamicMenu = $.fn.dropdown.settings.templates.menu;
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$.fn.dropdown.settings.templates.menu = function(response, fields, preserveHTML, className) {
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const ret = defaultCreateDynamicMenu(response, fields, preserveHTML, className);
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const $wrapper = $('<div>').append(ret);
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const $items = $wrapper.find('> .item');
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$items.each((_, item) => {
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prepareMenuItem($(item));
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});
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return $wrapper.html();
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};
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function attachOneDropdownAria($dropdown) {
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if ($dropdown.attr('data-aria-attached')) return;
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$dropdown.attr('data-aria-attached', 1);
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const $textSearch = $dropdown.find('input.search').eq(0);
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const $focusable = $textSearch.length ? $textSearch : $dropdown; // see comment below
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if (!$focusable.length) return;
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// prepare menu list
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const $menu = $dropdown.find('> .menu');
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if (!$menu.attr('id')) $menu.attr('id', generateAriaId());
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// dropdown has 2 different focusing behaviors
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// * with search input: the input is focused, and it works perfectly with aria-activedescendant pointing another sibling element.
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// * without search input (but the readonly text), the dropdown itself is focused. then the aria-activedescendant points to the element inside dropdown
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// expected user interactions for dropdown with aria support:
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// * user can use Tab to focus in the dropdown, then the dropdown menu (list) will be shown
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// * user presses Tab on the focused dropdown to move focus to next sibling focusable element (but not the menu item)
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// * user can use arrow key Up/Down to navigate between menu items
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// * when user presses Enter:
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// - if the menu item is clickable (eg: <a>), then trigger the click event
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// - otherwise, the dropdown control (low-level code) handles the Enter event, hides the dropdown menu
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// TODO: multiple selection is not supported yet.
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$focusable.attr({
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'role': 'menu',
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'aria-haspopup': 'menu',
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'aria-controls': $menu.attr('id'),
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'aria-expanded': 'false',
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});
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if ($dropdown.attr('data-content') && !$dropdown.attr('aria-label')) {
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$dropdown.attr('aria-label', $dropdown.attr('data-content'));
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}
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$menu.find('> .item').each((_, item) => {
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prepareMenuItem($(item));
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});
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// update aria attributes according to current active/selected item
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const refreshAria = () => {
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const isMenuVisible = !$menu.is('.hidden') && !$menu.is('.animating.out');
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$focusable.attr('aria-expanded', isMenuVisible ? 'true' : 'false');
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let $active = $menu.find('> .item.active');
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if (!$active.length) $active = $menu.find('> .item.selected'); // it's strange that we need this fallback at the moment
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// if there is an active item, use its id. if no active item, then the empty string is set
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$focusable.attr('aria-activedescendant', $active.attr('id'));
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};
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$dropdown.on('keydown', (e) => {
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// here it must use keydown event before dropdown's keyup handler, otherwise there is no Enter event in our keyup handler
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if (e.key === 'Enter') {
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let $item = $dropdown.dropdown('get item', $dropdown.dropdown('get value'));
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if (!$item) $item = $menu.find('> .item.selected'); // when dropdown filters items by input, there is no "value", so query the "selected" item
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// if the selected item is clickable, then trigger the click event. in the future there could be a special CSS class for it.
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if ($item && $item.is('a')) $item[0].click();
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}
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});
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// use setTimeout to run the refreshAria in next tick (to make sure the Fomantic UI code has finished its work)
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const deferredRefreshAria = () => { setTimeout(refreshAria, 0) }; // do not return any value, jQuery has return-value related behaviors.
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$focusable.on('focus', deferredRefreshAria);
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$focusable.on('mouseup', deferredRefreshAria);
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$focusable.on('blur', deferredRefreshAria);
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$dropdown.on('keyup', (e) => { if (e.key.startsWith('Arrow')) deferredRefreshAria(); });
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}
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export function attachDropdownAria($dropdowns) {
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$dropdowns.each((_, e) => attachOneDropdownAria($(e)));
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}
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export function attachCheckboxAria($checkboxes) {
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$checkboxes.checkbox();
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// Fomantic UI checkbox needs to be something like: <div class="ui checkbox"><label /><input /></div>
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// It doesn't work well with <label><input />...</label>
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// To make it work with aria, the "id"/"for" attributes are necessary, so add them automatically if missing.
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// In the future, refactor to use native checkbox directly, then this patch could be removed.
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for (const el of $checkboxes) {
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const label = el.querySelector('label');
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const input = el.querySelector('input');
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if (!label || !input || input.getAttribute('id')) continue;
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const id = generateAriaId();
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input.setAttribute('id', id);
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label.setAttribute('for', id);
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}
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}
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