Building Tools with GitHub

Chapter 9. JavaScript and the Git Data API

Applications utilizing the GitHub API will typically reside inside a server. You are not limited, however, to accessing the API from within server-side programming languages exclusively. The GitHub API works perfectly well from within a web browser context as well, and the UI to your application comes for free if you know a little HTML. In this chapter we discuss how to use the unofficial JavaScript client library to access the GitHub API and build a single-page application (SPA), which we host entirely on GitHub.

The main weakness of JavaScript has always been testability. Mainly due to the asynchronous nature of JavaScript, writing tests has never been easy; polling for changes when a callback returns was until recently the best way to test nonlinear code. But recent toolkits like AngularJS and promise-based libraries have made testing not only easy, but elegant as well. Building applications on top of third-party services makes testing even more important than it already was, and we’ll make sure to add testing to our application to verify the functionality works as we expect.

JavaScript should be generally accessible to most people who know other imperative programming languages. There is one feature, however, that can be challenging: the callback function. In JavaScript, functions are first-class objects, meaning they can be passed as arguments to other functions and stored as the value of a variable. You will find callbacks everywhere ...