Babylon.JS is undoubtedly the best JavaScript 3D games engine out there in the wild as of now for creating professional grade games that you can sell.
Babylon.JS is the outcome of David Catuhe’s love for 3D gaming engines. He has experience in creating 3D games engines in DirectX, OpenGL, and Silverlight etc. and has finally created one in JavaScript. Some of the key features of Babylon.js framework include scene graphs with lights, cameras, materials and meshes, collisions engine, physics engine, audio engine and optimization engine at the core. There is a Babylon.js playground available as well to try your hands on with this 3D gaming engine. You can grab the source code for free at babylon’s github repository.