Recently I've been looking into the field of Visual Regression Testing. I intend to give it a shot developing a tool that compares the visual representation of a site (a screenshot, for example) to the provided design to see if they're a match.
A few years back I had a chance to develop an interactive art installation with OpenFrameworks, which has the capability of proper graphical processing. My question is, though - is there any decent alternative to OpenFrameworks in JavaScript?
openFrameworks now supports Javascript / Browser via Emscripten http://arturocastro.net/files/of-emscripten/
Also, check out p5.js (an updated processing for js) http://hello.p5js.org/
There are (too) many choices, here is a list of drawing (and more) libraries. The three most popular ones are probably Processing.js, Raphael.js and Paper.js.
It's always good to have a look on game engines as well (turbulenz seems promising to me). Working with WebGL is a good choice when performances matters (Three.js is popular, and Babylon.js seems promising).
And I really like shadertoys, although it is not the only option to play with shaders.
My personal opinion
I strongly recommend Paper.js since it is object oriented, this makes a big difference, everything is much simpler.
However, be aware that you might have performances issues if you have complex/highly detailed and animated scenes (same thing with Processing.js or Raphael.js, the problem being the performances with the canvas, not the library itself).
An SVG (or WebGL) based library could be a better fit in this case, you can see this thread (read the comments) for more information.
Processing.js is probably the closest thing you'll get to a JavaScript version of OpenFrameworks.
Well, there is now a new library that is like processing but complety javascript oriented.
p5.js
Its simmilar to processing. The beta is outthere.
Oficial website : http://p5js.org/
Here is the youtube intro : https://www.youtube.com/watch?v=8j0UDiN7my4
