tts.ts
1,727 bytes
| 1 | export interface SpeakCallbacks { |
|---|---|
| 2 | onStart?: () => void |
| 3 | onEnd?: () => void |
| 4 | } |
| 5 | |
| 6 | export function selectVoice( |
| 7 | voices: readonly SpeechSynthesisVoice[], |
| 8 | preferredLanguage: string, |
| 9 | ): SpeechSynthesisVoice | null { |
| 10 | const preferred = preferredLanguage.trim().toLowerCase() |
| 11 | const preferredBase = preferred.split('-')[0] ?? '' |
| 12 | let best: SpeechSynthesisVoice | null = null |
| 13 | let bestScore = -1 |
| 14 | |
| 15 | for (const voice of voices) { |
| 16 | const language = voice.lang.toLowerCase() |
| 17 | const languageBase = language.split('-')[0] ?? '' |
| 18 | let score = 0 |
| 19 | if (preferred && language === preferred) score += 120 |
| 20 | else if (preferredBase && languageBase === preferredBase) score += 80 |
| 21 | if (voice.default) score += 20 |
| 22 | if (/natural/i.test(voice.name)) score += 1 |
| 23 | |
| 24 | if (score > bestScore) { |
| 25 | bestScore = score |
| 26 | best = voice |
| 27 | } |
| 28 | } |
| 29 | |
| 30 | return best |
| 31 | } |
| 32 | |
| 33 | function pickVoice(): SpeechSynthesisVoice | null { |
| 34 | return selectVoice(window.speechSynthesis.getVoices(), navigator.language) |
| 35 | } |
| 36 | |
| 37 | export function speak(text: string, callbacks: SpeakCallbacks = {}): void { |
| 38 | if (!('speechSynthesis' in window)) return |
| 39 | window.speechSynthesis.cancel() |
| 40 | const utterance = new SpeechSynthesisUtterance(text) |
| 41 | const voice = pickVoice() |
| 42 | if (voice) { |
| 43 | utterance.voice = voice |
| 44 | utterance.lang = voice.lang |
| 45 | } else if (navigator.language) { |
| 46 | utterance.lang = navigator.language |
| 47 | } |
| 48 | utterance.rate = 1 |
| 49 | utterance.pitch = 1 |
| 50 | utterance.onstart = () => callbacks.onStart?.() |
| 51 | utterance.onend = () => callbacks.onEnd?.() |
| 52 | utterance.onerror = () => callbacks.onEnd?.() |
| 53 | window.speechSynthesis.speak(utterance) |
| 54 | } |
| 55 | |
| 56 | export function stopSpeaking(): void { |
| 57 | if ('speechSynthesis' in window) window.speechSynthesis.cancel() |
| 58 | } |
| 59 | |