I am making a drawing app with HTML5 CSS and JS. The purpose of it is to act like the usual drawing app; draw, layers, line size, and a paint bucket fill.

I don't know how to do this. I have tried ctx.fillRect but it cant fill in between the lines, and I don't think I can make a variable for the width and height of the lines. I have searched the entire face of Google and have found nothing.

Stack Overflow is my last hope. Please help.