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Discussion narration created a new Audio element per line, so on mobile every line after the first had its programmatic play() refused with NotAllowedError: the dialogue went silent while the lesson kept advancing. This is the discussion side of #1474, which #1477 fixed for the narration player. One module-scoped element now serves every line, kept separate from the narration element in AudioPlayer so neither can cut the other off. Because element identity can no longer tell lines apart, the stale-event guard became a per-line token, handlers are assigned rather than added (a listener would accumulate once per line), and finish()/cleanup() release the line by removing the source attribute and reloading instead of leaving the element pointed at the page's own URL. Co-authored-by: talkman <jaxgen@163.com> Co-authored-by: wyuc <wang-yc24@mails.tsinghua.edu.cn>
55 lines
2.1 KiB
TypeScript
55 lines
2.1 KiB
TypeScript
/**
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* The audio element discussion playback reuses for every line.
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*
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* Mobile autoplay policies only cover an element that a user gesture has
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* reached, so an element minted per line gets its programmatic `play()` refused
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* with NotAllowedError from the second line on: the discussion goes silent
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* while the lesson keeps advancing. One element, handed every line, stays
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* playable for the rest of the lesson.
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*
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* Deliberately separate from the narration element in `AudioPlayer`: sharing a
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* single element would let a discussion line cut the narrator off, and vice
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* versa.
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*
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* Module scope means one element per page, so there must be a single consumer:
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* a second mounted hook would overwrite the first one's source and handlers, and
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* the first would then wait forever.
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*/
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let element: HTMLAudioElement | null = null;
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/** The discussion element, created on first use and reused by every line. */
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export function getDiscussionAudioElement(): HTMLAudioElement {
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if (!element) {
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element = new Audio();
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element.preload = 'auto';
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}
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return element;
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}
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/**
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* Drops the element so a test starts from a clean module state. The element is
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* module scoped (one per page, like the narration player), so without this a
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* later test would silently inherit the first test's stubbed element.
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*/
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export function resetDiscussionAudioElementForTests(): void {
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element = null;
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}
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/**
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* Releases a line's state from the element without discarding the element.
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*
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* An empty string is not "no source": `src = ''` points the element at the
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* page's own URL and starts a load that fails asynchronously with an `error`
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* event. On a reused element that late error can land on the *next* line's
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* handler and finish it before it is heard. Removing the attribute and calling
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* `load()` leaves the element idle and silent instead — the same shape as
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* `stopAudioElement()` in `lib/utils/audio-player.ts`.
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*/
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export function releaseDiscussionAudioLine(element: HTMLAudioElement): void {
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element.onended = null;
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element.onerror = null;
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element.pause();
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element.removeAttribute('src');
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element.load?.();
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}
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