Neat, although the fun begins when you try to fill them since you cannot just ignore the primitives anymore if a vertex touches the near plane but instead you have to clip the primitive :-). Also without a z-buffer hidden surface removal becomes tricky if you want to avoid bad overlaps.

For fun i made a 3D thing a few years ago, you can check it here:

http://runtimeterror.com/pages/badsector/nyan/test.html

The code does the clipping part (triRender function) although HSR is painter's algorithm with a simple sorting (triSort) with a heuristic (triCompare) that i came out through trial and error (because of the distortion introduced by the perspective projection this doesn't always work and IIRC i'd need to actually split the polygons for better result but i was too lazy for that :-P).

Note that i wrote this for fun a few years ago, i am not a web dev nor really follow web tech. This is the biggest block of JavaScript code i've written for years :-P.