The new Azure Search service is a nice 'search as a service' offering from Microsoft. Just add your documents, and then run some queries. It's exposed as a REST API which talks JSON :¬D
It has a free tier, limited to 3 indexes and 10,000 documents, but you can of course start paying the money and index more stuff.
I just wrote a JavaScript client (I couldn't find a Microsoft one) to connect to the API, let's explore how we can use it.
Note this article assumes you are familiar with writing JavaScript for node.js and the browser.