In the Kerala JS: September meetup, I gave a talk on Unit Testing with Mocha. My primary goal of this talk was to give a introduction to testing in JavaScript.
The slides of my talk are available below
The sinppet I used to show the testing JS in browser is available as JsBin.
You can also take a look at Testing jQuery ajax with mocha and sinon in which I explained how to test a Ajax functionality using Sinon.