window1.html

<!DOCTYPE html>
<html>
  <head>
    <meta charset="UTF-8">
    <title>Source </title>
  </head>
  <body>
    <center>
    <h1>WINDOW 1</h1>
<canvas id="source" width="300" height="300" ></canvas>
<p>
This is the source canvas , we want to copy it's content inside the other window's canvas
</p>
</center>
  </body>

  <script>
    // You can also require other files to run in this process
    require('./renderer1.js')
  </script>
</html>