WebMonkeys | Massively parallel GPU programming on JavaScript , simple | Architecture library

First off, WebGL only rasterizes points, lines, and triangles. Using WebGL to do non rasterization (GPGPU) is basically a matter of realizing that the inputs to WebGL are data from arrays and the output, a 2D rectangle of pixels is also really just a 2D array so by creatively providing non graphic data and creatively rasterizing that data you can do non-graphics math.

WebGL is parallel in 2 ways.

1. it's running on a different processor, the GPU, while it's computing something your CPU is free to do something else.

2. GPUs themselves compute in parallel. A good example if you rasterize a triangle with 100 pixels the GPU can process each of those pixels in parallel up to the limit of that GPU. Without digging too deeply it looks like an NVidia 1080 GPU has 2560 cores so assuming they are not specialized and assuming the best case one of those could compute 2560 things in parallel.

As for an example all WebGL apps are using parallel processing by points (1) and (2) above without doing anything special.

Adding 10 to 10000 elements though in place is not what WebGL is good at because WebGL can't read from and write to the same data during one operation. In other words, your example would need to be