tts-react

tts-react

tts-react provides a hook (useTts) and component (TextToSpeech) to convert text to speech. In most cases you want the hook so you can use custom styling on the audio controls.

By default tts-react uses the SpeechSynthesis and SpeechSynthesisUtterance API's. You can fallback to the HTMLAudioElement API by providing a fetchAudioData prop to the hook or component.

Install

npm i react react-dom tts-react

Documentation

morganney.github.io/tts-react

Example

Hook

import { useTts } from 'tts-react'
import type { TTSHookProps } from 'tts-react'

interface HookExampleProps extends TTSHookProps {
  highlight?: boolean
}

const HookExample = ({ children, highlight = false }: HookExampleProps) => {
  const { ttsChildren, state, onPlay, onStop, onPause } = useTts({
    children,
    markTextAsSpoken: highlight
  })

  return (
    <div>
      {state.isReady && (
        <>
          <button onClick={onPlay}>Play</button>
          <button onClick={onPause}>Pause</button>
          <button onClick={onStop}>Stop</button>
        </>
      )}
      {ttsChildren}
    </div>
  )
}

const App = () => {
  return <HookExample highlight>Some text to be spoken.</HookExample>
}

Component

import { TextToSpeech, Positions, Sizes } from 'tts-react'

const App = () => {
  return (
    <TextToSpeech
      markTextAsSpoken
      align="vertical"
      size={Sizes.SMALL}
      position={Positions.TL}>
      <p>Some text to be spoken.</p>
    </TextToSpeech>
  )
}

useTts

The hook returns the internal state of the audio being spoken, getters/setters of audio attributes, callbacks that can be used to control playing/stopping/pausing/etc. of the audio, and modified children if using markTextAsSpoken. The parameters accepted are described in the Props section. The response object is described by the TTSHookResponse type.

const useTts = ({
  lang,
  voice,
  children,
  markColor,
  markBackgroundColor,
  onError,
  onMuted,
  fetchAudioData,
  autoPlay = false,
  markTextAsSpoken = false
}: TTSHookProps): TTSHookResponse => {
  // ...
  return {
    get,
    set,
    state,
    spokenText,
    ttsChildren,
    onPlay,
    onStop,
    onPause,
    onReset,
    onPlayPause,
    onMuted: onMutedHandler
  }
}

interface TTSHookResponse {
  set: {
    lang: (value: string) => void
    rate: (value: number) => void
    pitch: (value: number) => void
    volume: (value: number) => void
    preservesPitch: (value: boolean) => void
  }
  get: {
    lang: () => string
    rate: () => number
    pitch: () => number
    volume: () => number
    preservesPitch: () => boolean
  }
  state: TTSHookState
  spokenText: string
  onPlay: () => void
  onStop: () => void
  onPause: () => void
  onReset: () => void
  onMuted: () => void
  onPlayStop: () => void
  onPlayPause: () => void
  ttsChildren: ReactNode
}
interface TTSHookState {
  voices: SpeechSynthesisVoice[]
  boundary: BoundaryUpdate
  isPlaying: boolean
  isPaused: boolean
  isMuted: boolean
  isError: boolean
  isReady: boolean
}
interface TTSBoundaryUpdate {
  word: string
  startChar: number
  endChar: number
}

fetchAudioData

Using fetchAudioData will bypass SpeechSynthesis and use the HTMLAudioElement.

(spokenText: string) => Promise<TTSAudioData>

When using fetchAudioData it must return TTSAudioData which has the following shape:

interface PollySpeechMark {
  end: number
  start: number
  time: number
  type: 'word'
  value: string
}
interface TTSAudioData {
  audio: string
  marks?: PollySpeechMark[]
}

The audio property must be a URL that can be applied to HTMLAudioElement.src, including a data URL. If using markTextAsSpoken then you must also return the marks that describe the word boundaries. PollySpeechMarks have the same shape as the Speech Marks used by Amazon Polly, with the restriction that they must be of type: 'word'.

Props

Most of these are supported by the useTts hook, but those marked with an asterisk are exclusive to the TextToSpeech component.

_{* Only applies to TextToSpeech component.}

Name	Required	Type	Default	Description
children	yes	ReactNode	none	Provides the text that will be spoken.
lang	no	string	The one used by SpeechSynthesisUtterance.lang.	Sets the SpeechSynthesisUtterance.lang. Overrides voice when set and voice.lang does not match lang.
voice	no	SpeechSynthesisVoice	None or the voice provided by audio from TTSAudioData.	The voice heard when the text is spoken. Calling set.lang may override this value.
autoPlay	no	boolean	false	Whether the audio of the text should automatically be spoken when ready.
markTextAsSpoken	no	boolean	false	Whether the word being spoken should be highlighted.
markColor	no	string	none	Color of the text that is currently being spoken. Only applies with markTextAsSpoken.
markBackgroundColor	no	string	none	Background color of the text that is currently being spoken. Only applies with markTextAsSpoken.
fetchAudioData	no	(text: string) => Promise<TTSAudioData>	none	Function to return the optional SpeechMarks[] and audio URL for the text to be spoken. See fetchAudioData for more details.
*allowMuting	no	boolean	true	Whether an additional button will be shown on the component that allows muting the audio. Calls onMuted when clicked.
onMuted	no	(wasMuted: boolean) => void	none	Callback when the user clicks the mute button shown from allowMuting being enabled. Can be used to toggle global or local state like whether autoPlay should be enabled.
onError	no	(evt: CustomEvent<string>) => void	none	Callback when there is an error of any kind playing the spoken text. The error message (if any) will be provided in evt.detail.
*align	no	'horizontal' | 'vertical'	'horizontal'	How to align the controls within the TextToSpeech component.
*size	no	'small' | 'medium' | 'large'	'medium'	The relative size of the controls within the TextToSpeech component.
*position	no	'topRight' | 'topLeft' | 'bottomRight' | 'bottomLeft'	'topRight'	The relative positioning of the controls within the TextToSpeech component.
*useStopOverPause	no	boolean	false	Whether the controls should display a stop button instead of a pause button. On Android devices, SpeechSynthesis.pause() behaves like cancel(), so you can use this prop in that context.

FAQs

Why does markTextAsSpoken sometimes highlight the wrong word?

The SpeechSynthesisUtterance boundary event may fire with skewed word boundaries for certain combinations of spokenText and lang or voice props. If you check the value of state.boundary.word in these cases, you will find the event is firing at unexpected boundaries, so there is no real solution other than to find a suitable voice for your given spokenText.

Why does markTextAsSpoken not work on Chrome for Android?

This is a known issue by the Chromium team that apparently they are not going to fix. You can use fetchAudioData to fallback to the HTMLAudioElement, or try a different browser.

Why can I not pause the audio when using SpeechSynthesis on Firefox and Chrome for Android?

See the compat table on MDN for SpeechSynthesis.pause().

In Android, pause() ends the current utterance. pause() behaves the same as cancel().

You can use the hook useTts to build custom controls that do not expose a pause, but only stop. If using the TextToSpeech component use the useStopOverPause prop for Android devices.