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 SpeechRecognitionAlternative
s 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 compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|
Basic support | 33 [1] | 44 (44) [2] | No support | No support | No support |
Feature | Android | Chrome | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | ? | (Yes)[1] | ? | 2.5 | No support | No support | No support |
- [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"