Question

How can I make a canvas transparent? I need to because I want to put two canvases on top of one another.

Answer 1

Canvases are transparent by default.

Try setting a page background image, and then put a canvas over it. If nothing is drawn on the canvas, you can fully see the page background.

Think of a canvas as like painting on a glass plate.

To clear a canvas after having drawn on it, just use clearRect:

const context = canvas.getContext('2d');
context.clearRect(0, 0, canvas.width, canvas.height);