voice-command-recognizer/README.md

React HOC for voice command recognition. Based on Web Speech API's Speech Recognizer, using Annyang

# voice-command-recognizer
React component to recognize voice commands based on the Web Speech API (`SpeechRecognizer`).

## Dependencies

It relies on [`annyang`](https://github.com/TalAter/annyang) (Speech Recognition library by [TalAlter](https://twitter.com/TalAter)) for command matching.

It enhances the command recognition by adding a `fuzzyMatchThreshold` feature. This prop allows to specify a certain tolerance for what the user says to be considered as correct.

The string comparison is using [`fuzzyset.js`](https://glench.github.io/fuzzyset.js/) by [@Glench](https://twitter.com/Glench) with its default config.

## How the component works

It's an HOC and you are capable of just conditionally rendering things inside it, based on its state (as with any other HOC).

You can either set the component to be listening to everything or only enable listening once the user says a certain `keyphrase` that you can define through the component `props`. The `keyphrase` needs to be said before each command. The `voice-command-recognizer` stops listening after the first successfully understood command. So, the `keyphrase` if set, is expected to be said between the commands that are intended to be ran.

You can also define a percentage of accuracy for what the user says and either run a custom action when that threshold is reached or just consider that as correct. It's useful for those cases when the user might not be a native english speaker and you'd like to be a bit more forgiving on pronunciation. :)

`voice-command-recognizer` also provides a hook when the `keyphrase` has been detected and the component is ready to listen to the commands provided (`onRecognizerEnabled`).

### Props:

- `commands`: The commands to be accepted and the function to be run for each. Different formats are accepted, see the _Commands_ section below.
- `keyCommand`: The command that would enable the component to listen. When said again, it would make the component stop listening.
- `startVoiceRecognition`: Flag that allows to start/pause the recognition.
- `fuzzyMatchThreshold`: A number (from 0 to 1) that determines how exact what the user says need to be.
- `onPermissionBlocked`: The function to be run if the browser denies access to the microphone.
- `onPermissionDenied`: The function to be run if the user denies access to the microphone.
- `onStart`: It's triggered when `SpeechRecognizer` triggers its `onstart` event. It's a way to update your application once the speech recognition is started (i.e.: the browser can hear you).
- `onRecognizerEnabled`: For the case when a `keyphrase` is provided, this `prop` expects a function that'd be executed once `voice-command-recognizer` has detected the `keyphrase` being said and it's ready to listen for a command.
- `onRecognizerDisabled`: For the case when a `keyphrase` is provided, this `prop` expects a function that'd be executed once the actual command that was intended to be executed has been detected and the recognizer goes back to waiting on the `keyphrase` to be said.
- `onFuzzyMatch`: Action to be ran when what the user is at least `fuzzyMatchThreshold`. If there's not an action provided, the component will trigger the command that's closes to what the user said.
- `onNotMatch`: Action to be run when there's not a full match neither a fuzzy match with any of the available commands.

#### `commands` prop

The format expected for the command would be as follows:

```
{
  phrases: ['search', 'look for', 'find'],
  callback: () => {
    const { counter } = this.state;

    this.setState({
      counter: counter + 1,
    });
  },
}
```

`phrases` are basically the commands that when said would trigger the function that's in `callback` attribute.

They don't need to be specific words, but you can make it more general and use either regexes or spats.

This is supported through Annyang. Have a look at their [doc's](https://github.com/TalAter/annyang/tree/master/docs#good-to-know) for how the commands can be defined.

## Next steps

- [ ] Update the current implementation on [Guess the Movie](https://github.com/loqtor/guess-the-movie) to use this component.