How to copy canvas game?

Question

JavaScript

There is a game on canvas, please give information on how to copy it? Where to begin?
Here is https://king-vulkan.com/games/demo/book_of_ra

<code><div class="canvas-box" style="width: 765px; height: 553px; top: 56px;">
      <canvas class="canvas" id="idcanvas" width="1660" height="1200" style="touch-action: none; cursor: inherit;"></canvas>
    </div></code>