window.onload = () => {

play.onclick = (e) => {
  
  var u = new SpeechSynthesisUtterance();
  u.text = 'Hello World. This is a large test.';
  u.lang = 'en-US';
  u.rate = 1.0;
  let boundaryIdx = 0;
  u.onboundary = function(event) {
    let word = u.text.substring(boundaryIdx, event.charIndex);
    boundaryIdx = event.charIndex;
    console.log('boundary', word, event); 
  };
  speechSynthesis.speak(u);
  
};
  
};