Repeatedly polling server with ajax

I’ve made a small fiddle that illustrates repeatedly polling a server asynchronously once every second with the ability to pause and resume for posterity. For more advanced functionality, including long-polling then SignalR is your man, but for something simple this does the job. The code is also reproduced here:

Testing asynchronous JavaScript

By making AJAX calls directly to the server from your JavaScript view-model it can be impossible to get the code under test. A simple solution is to fake the calls and make them synchronous. This example view-model for a library takes a function that will make a call to the server to check out a book […]