Lower and Upper Canvas in FabricJS

https://miro.medium.com/v2/resize:fit:1316/format:webp/1*ny8DZl4ZNsqYtnQVeWsD4w.png

The id of the lower canvas is the id that we used to reference the canvas element with. So, if we were to change the id to something like “meowwww”, the id of lower-canvas class would(obviously) change too.

So, as you might have guessed by now, it is actually the lower canvas on which all of our objects are drawn onto. The upper canvas comes into picture where there are group selections and handles things on the fabric side.

참고
https://medium.com/@aditi.6ti/lower-and-upper-canvas-in-fabricjs-8a62821bfc5c