Is there a way to draw an HTML5 canvas on another canvas faster than toDataUrl?

Question

I have a few pages that break up the drawing of a high quality image into many small sections so the browser doesn't lock up or cause problem for taking too long.
One example is the download feature on this:
https://code.sololearn.com/W6e6xWN0T7Jv/#html
toDataUrl works but it seems to take a while. I want to draw the data with no error and converting to and from PNG or JPG seems like a waste of time if my goal is just to copy all pixels.
Is there a faster way to copy the contents of 1 canvas to another without toDataUrl?

Answer 1

I'm not sure if this would perform better but if I remember well you should be able to use the canvas itself as source:
ctx2d.drawImage(webglCanvas,0,0)

Answer 2

Thanks, Kevin.
When the other drawing work is much faster, switching from toDataUrl to just using the canvas directly makes the process multiples faster.