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How to Use the Web Speech API in HTML5

The Voice Dictation app uses the Web Speech API to convert your spoken words into text. There’s a simple JavaScript API that lets you integrate Speech Recognition on any website.

The Web Speech API is currently implemented in Chrome and Firefox.


<div>
  <a href="#" id="start_button" onclick="startDictation(event)">Dictate</a>
</div>

<div id="results">
  <span id="final_span" class="final"></span>
  <span id="interim_span" class="interim"></span>
</div>

<script type="text/javascript">
var final_transcript = '';
var recognizing = false;

if ('webkitSpeechRecognition' in window) {

  var recognition = new webkitSpeechRecognition();

  recognition.continuous = true;
  recognition.interimResults = true;

  recognition.onstart = function() {
    recognizing = true;
  };

  recognition.onerror = function(event) {
    console.log(event.error);
  };

  recognition.onend = function() {
    recognizing = false;
  };

  recognition.onresult = function(event) {
    var interim_transcript = '';
    for (var i = event.resultIndex; i < event.results.length; ++i) {
      if (event.results[i].isFinal) {
        final_transcript += event.results[i][0].transcript;
      } else {
        interim_transcript += event.results[i][0].transcript;
      }
    }
    final_transcript = capitalize(final_transcript);
    final_span.innerHTML = linebreak(final_transcript);
    interim_span.innerHTML = linebreak(interim_transcript);
    
  };
}

var two_line = /\n\n/g;
var one_line = /\n/g;
function linebreak(s) {
  return s.replace(two_line, '<p></p>').replace(one_line, '<br>');
}

function capitalize(s) {
  return s.replace(s.substr(0,1), function(m) { return m.toUpperCase(); });
}

function startDictation(event) {
  if (recognizing) {
    recognition.stop();
    return;
  }
  final_transcript = '';
  recognition.lang = 'en-US';
  recognition.start();
  final_span.innerHTML = '';
  interim_span.innerHTML = '';
}
</script>