importmodules.html

// irand.html

<script>
  modularize(function() {
    // whatever we return constitutes our `module`
    return function(n) {
      return Math.floor(Math.random() * n);
    }
  });
</script>

// text.html

<!-- imports handle dependency management and network access -->
<link rel="import" href="irand.html">

<script>
  // create a module that uses 'irand'
  modularize(['irand'], function(irand) {
    // whatever we return constitutes our `module`
    return {
      get text() {
        return ['Ahoy-hoy', 'Excellent', 'Gyrocopter to Siam'][irand(3)];
      }
    }
  });
</script>

// index.html

<link rel="import" href="text.html">

<script>
  using(['text'], function(text) {
    document.write(text.text);
  });
</script>