The OP is real time ray tracing which is running between 30-60FPS on my macbook air while moving the camera and objects around.
Your link appears to be a basic ray tracer which anyone who has taken an intro to computer graphics course in college is likely required to implement and would only need a javascript canvas. To be honest I have no idea how much OPs real-time ray tracing differs in complexity from traditional ray tracing.
You don't even need a canvas.
You could simulate pixels with divs if that's all you had. Or you could create an image in memory and save to file. You could write the text for it and save as SVG.
For a CPU based ray tracer, you don't need any output capability at all(unless you want it to be interactive, which school assignment raytracers usually don't have to).