livewire-material/resources/js/search.js

/**
 * `materialSearch`: the behaviour of `<x-search>` — a search bar that opens into a search view.
 *
 * Focus or a press on the bar opens the view; Escape, the back arrow, a press outside, focus
 * leaving the search, or choosing a result closes it. ArrowDown from the input moves into the
 * results and the arrow keys walk them; ArrowUp past the first result returns to the input. On a
 * compact window (below `medium`, 600px) the view is full screen and modal: focus stays in it and
 * the page behind does not scroll — M3 docks the view from medium upwards. The results themselves
 * are the caller's, rendered by Livewire into the view as the query changes.
 *
 * Because the results arrive from the server, nothing in the page tells a screen reader they are
 * there; M3 asks that it be told. A MutationObserver counts the list items whenever the view's DOM
 * settles and writes "N results" into the polite live region the view renders, which is the one
 * announcement M3's search accessibility page names.
 */
import { upTo } from './breakpoints.js'

const FOCUSABLE = 'a[href], button:not([disabled]), input:not([disabled]), select:not([disabled]), textarea:not([disabled]), [tabindex]:not([tabindex="-1"])'

const CHOOSES = 'a[href], button:not([disabled]), [data-list-open]'

// A close hands focus back to the input: Escape does, and so does the full-screen view's focus trap
// when it lets go, a moment later. Focus arriving this soon after a close is that, not someone
// coming to search.
const RETURN_GUARD_MS = 250

// A Livewire morph replaces the results in several mutations; wait for the batch to end before
// counting, so the live region speaks once.
const SETTLE_MS = 120

document.addEventListener('alpine:init', () => {
    window.Alpine.data('materialSearch', (docked = false, announce = {}) => ({
        open: false,
        compact: false,
        closedAt: -Infinity,
        announcement: '',
        observer: null,
        settle: null,

        init() {
            const query = upTo('medium')

            this.compact = query.matches
            query.addEventListener('change', (event) => (this.compact = event.matches))

            this.observer = new MutationObserver(() => this.countLater())
            this.observer.observe(this.$refs.view, { childList: true, subtree: true, characterData: true })

            this.$watch('open', () => this.countLater())
        },

        destroy() {
            this.observer?.disconnect()
            clearTimeout(this.settle)
        },

        countLater() {
            clearTimeout(this.settle)
            this.settle = setTimeout(() => this.count(), SETTLE_MS)
        },

        count() {
            if (! this.open) {
                this.announcement = ''

                return
            }

            const results = this.$refs.view.querySelector('[data-search-results]')
            const items = results ? results.querySelectorAll('[role="listitem"], li') : []
            const total = items.length || (results ? this.results().length : 0)

            this.announcement = total === 0
                ? (announce.none ?? '')
                : total === 1
                    ? (announce.one ?? '')
                    : (announce.many ?? '').replace(':count', total)
        },

        get fullScreen() {
            return this.open && this.compact && !docked
        },

        show() {
            this.open = true
        },

        focused() {
            if (performance.now() - this.closedAt > RETURN_GUARD_MS) {
                this.show()
            }
        },

        close(refocus = false) {
            this.open = false
            this.closedAt = performance.now()

            if (refocus) {
                this.$refs.input.focus()
            }
        },

        clear() {
            const input = this.$refs.input

            input.value = ''
            input.dispatchEvent(new Event('input', { bubbles: true }))
            input.focus()
        },

        results() {
            return [...this.$refs.view.querySelectorAll(FOCUSABLE)].filter((element) => element.getClientRects().length > 0)
        },

        step(delta) {
            const results = this.results()
            const index = results.indexOf(document.activeElement)

            if (results.length === 0) {
                return
            }

            if (index === -1) {
                results[delta > 0 ? 0 : results.length - 1].focus()
            } else if (index + delta < 0) {
                this.$refs.input.focus()
            } else {
                results[Math.min(index + delta, results.length - 1)].focus()
            }
        },

        choose(event) {
            if (event.target.closest(CHOOSES)) {
                this.close()
            }
        },

        leave(event) {
            if (event.relatedTarget && !this.$root.contains(event.relatedTarget)) {
                this.close()
            }
        },
    }))
})