This page is a quick and minimalistic way of interacting with HTML canvases. Rather than spinning one up from scratch just to do some mathy art, this serves as a template.
This page is written entirely in client-side Javascript, so whatever you write locally stays local. The page provides a function g(x, y) where x and y are integers in the range [0, width) and [0, height), respectively. The default width and height harken back to DOS days when 320x240 was a low-res standard. The drawscale is a multiplier for the size of the canvas, but doesn't affect any of the math. Width and height do, however, as they are the resolution of the image. Crazy high values may affect render times.
The code uses eval to resolve whatever Javascript is provided in the input box to resolve either an integer or an array of three integers. The integer approach uses QBasic colors (the previews appear on the home screen as a reminder). The array approach uses the rgb function to specify colors, where RGB values range from 0 to 255.