keywords/const.html

<!DOCTYPE html>
<html>
<head>
  <meta content="text/html;charset=utf-8" http-equiv="Content-Type">
  <title>Javascript: this</title>
  <script type="text/javascript">

    function print(text) {
      out.innerHTML += text + "<br>";
    }

    function main() {

      try {
        const foo = 42;
        print("foo = " + foo);
        foo = 1;
        print("foo = " + foo);

      }
      catch (e) {
        print("exception: " + e);
     // exception: TypeError: invalid assignment to const `foo'
      }
    }

  </script>
</head>
<body onload='main();'>

  <div id='out'>
  </div>

</body>
</html>