From Future Skill
The graphical output in the freecode editor uses the html canvas element with WebGL.
If you can not see any contents in the canvas make sure that your browser supports WebGL and that it is enabled. In Chrome for Windows it might help to enter chrome://flags/ and enable the "Override software rendering list" setting.
Instructions for how to create and manage canvas elements in your own implementations: https://app.futureskill.com/media/freecode_graphics_v3.pdf