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SpeechRecognition.maxAlternatives

This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

The maxAlternatives property of the SpeechRecognition interface sets the maximum number of SpeechRecognitionAlternatives provided per SpeechRecognitionResult.

The default value is 1.

Syntax

var myMaxAlternativeNumber = mySpeechRecognition.maxAlternatives;
mySpeechRecognition.maxAlternatives = 2;

Value

A number representing the maximum returned alternatives for each result.

Examples

This code is excerpted from our Speech color changer example.

var grammar = '#JSGF V1.0; grammar colors; public <color> = aqua | azure | beige | bisque | black | blue | brown | chocolate | coral | crimson | cyan | fuchsia | ghostwhite | gold | goldenrod | gray | green | indigo | ivory | khaki | lavender | lime | linen | magenta | maroon | moccasin | navy | olive | orange | orchid | peru | pink | plum | purple | red | salmon | sienna | silver | snow | tan | teal | thistle | tomato | turquoise | violet | white | yellow ;'
var recognition = new SpeechRecognition();
var speechRecognitionList = new SpeechGrammarList();
speechRecognitionList.addFromString(grammar, 1);
recognition.grammars = speechRecognitionList;
//recognition.continuous = false;
recognition.lang = 'en-US';
recognition.interimResults = false;
recognition.maxAlternatives = 1;

...

Specifications

Specification	Status	Comment
Web Speech API The definition of 'maxAlternatives' in that specification.	Draft

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	33 Prefixed 33 Prefixed Prefixed Requires the vendor prefix: webkit You'll need to serve your code through a web server for recognition to work.	?	No	No	No	No

	Mobile
	Android webview	Chrome for Android	Edge Mobile	Firefox for Android	Opera for Android	iOS Safari	Samsung Internet
Basic support	Yes Prefixed Yes Prefixed Prefixed Requires the vendor prefix: webkit You'll need to serve your code through a web server for recognition to work.	Yes Prefixed Yes Prefixed Prefixed Requires the vendor prefix: webkit You'll need to serve your code through a web server for recognition to work.	?	No	No	No	?

Firefox OS permissions

To use speech recognition in an app, you need to specify the following permissions in your manifest:

"permissions": {
  "audio-capture" : {
    "description" : "Audio capture"
  },
  "speech-recognition" : {
    "description" : "Speech recognition"
  }
}

You also need a privileged app, so you need to include this as well:

  "type": "privileged"

SpeechRecognition.maxAlternatives

Syntax

Value

Examples

Specifications

Browser compatibilityUpdate compatibility data on GitHub

Firefox OS permissions

See also