SpeechGrammarList

The SpeechGrammarList interface of the Web Speech API represents a list of SpeechGrammar objects containing words or patterns of words that we want the recognition service to recognize.

Grammar is defined using JSpeech Grammar Format (JSGF.) Other formats may also be supported in the future.

Constructor

SpeechGrammarList.SpeechGrammarList()

Creates a new SpeechGrammarList object.

Properties

SpeechGrammarList.length Read only

Returns the number of SpeechGrammar objects contained in the SpeechGrammarList.

Methods

SpeechGrammarList.item()

Standard getter — allows individual SpeechGrammar objects to be retrieved from the SpeechGrammarList using array syntax.

SpeechGrammarList.addFromURI()

Takes a grammar present at a specific URI and adds it to the SpeechGrammarList as a new SpeechGrammar object.

SpeechGrammarList.addFromString()

Takes a grammar present in a specific DOMString within the code base (e.g. stored in a variable) and adds it to the SpeechGrammarList as a new SpeechGrammar object.

Examples

In our simple Speech color changer example, we create a new SpeechRecognition object instance using the SpeechRecognition() constructor, create a new SpeechGrammarList, add our grammar string to it using the SpeechGrammarList.addFromString method, and set it to be the grammar that will be recognised by the SpeechRecognition instance using the SpeechRecognition.grammars property.

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;

Specifications

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

Browser compatibility

• [1] Speech recognition interfaces are currently prefixed on Chrome, so you'll need to prefix interface names appropriately, e.g. webkitSpeechRecognition; You'll also need to serve your code through a web server for recognition to work.
• [2] Can be enabled via the media.webspeech.recognition.enable flag in about:config, although note that currently speech recognition won't work on Desktop Firefox — it will be properly exposed soon, once the required internal permissions are sorted out.

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"

See also

• Web Speech API