What do I read to understand WebGL?

I am very new to WebGL and am extremely interested in doing some projects with it. I downloaded the OpenGL ES 2.0.25 manual to learn an much as I can. Of course, going to the actual spec for WegGL: https://www.khronos.org/registry/webgl/specs/1.0/ I see all of the references to OpenGL ES 2.0 manual pages. I take it that I must read those manual pages to truly understand what WebGL is/is doing. Is this true?

We need to be patient. Serious WebGL books are coming out in a few months, especially an edition by O’Reilly.
Check Amazon to see the future releases.

If you know OpenGL and JavaScript, WebGL is quite a small learning curve, so I’d recommend starting there.

The tutorials at http://learningwebgl.com/blog/?page_id=1217 are a good place to start.