This is the bare minimum code to get voice dictation up and running with Chrome's new speech recognition API. Copy and paste into the JavaScript console, call the function and away you go.

Basic JavaScript Dictation

function setupDictation() {
  var recognizer = new webkitSpeechRecognition();
  recognizer.continuous = true;
  recognizer.interimResults = true;
  recognizer.onresult = function(e) {
    if (e.results.length) {
      var lastResultIdx = e.resultIndex;
      var message = e.results[lastResultIdx][0].transcript;
      if(e.results[lastResultIdx].isFinal) {
        console.log(message);
      }
    }
  };
  recognizer.onend = function(e) {
    console.log('dictation ended');
  };
  recognizer.start();
}