Here’s a sample shadow mapping done on WebGL using Three.js library.
One would have thought that WebGL, which is OpenGL on web browsers, is a perfect recipe for disaster. However thanks to Three.js, I managed to whipped up this shadow mapping example in less than 2 hours (includes testing, cleaning up code, learning parts from scratch, etc).
And since Three.js already comes with essential functionalities, such as model loading, shadow mapping, phong based shading, trackball, etc, creating a working WebGL application seems to be easier than ever. And the resulting codes are clean and easy to read too! Kudos to Three.js 
Nevertheless, here’s the sample of shadow mapping with ply models:
 The dragon and Budai statues ply models are obtained from Stanford 3D scanning repository (https://graphics.stanford.edu/data/3Dscanrep/)
 Three.js (http://threejs.org)