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While chatting in a CodeNewbie Slack channel I realized that the question of what functional programming is in relation to object oriented programming is a question that comes up a lot and is an area of great confusion. For this reason, I wanted to write an article to hopefully help clear up this confusion, even if just for a little. What I came up with was 11 different versions of the same progra

These days, when the phrase "headless browser" is mentioned, you immediately think of PhantomJS, but - there are alternatives. In this article, I am going to introduce a nice alternative you can use on Linux which allows you to run real browsers - Firefox and Chrome, headless - using Xvfb. What's Wrong With PhantomJS? PhantomJS is great tool and is widely used by companies and developers around th

Writing programs to do static analysis on Javascript is easier now than ever, thanks to Esprima - the Javascript parser library. In this post, I'll demonstrate how to use Esprima to do something fairly simple - detect accidentally leaked global variables in a program. Accidentally leaked global variables happen when a value is assigned to an identifier without declaring the identifier as a variabl

JSDiff is an implementing of text comparison in Javascript, it is used in Mocha to implement colored diffs, and it's fairly easy to use. Let's say you have two strings: oldString and newString

Got Code? Until recently, Javascript had not had much of a module story, i.e., a good way of sharing code with others. I would say it doesn't have a great one even today. The Snippet You google for how to throttle in Javascript, and you get a blog post with 11 lines of magic you can copy-n-paste. Copy-n-pasting code into your project seems a little yucky - maybe better to fetch a file to clearly d

If you didn’t already know, Javascript functions double as object constructors. For example, to simulate a class in object-oriented programming, you would write Note: I avoid using semicolons because I am a heretic! Mislav argues my point for me here. Anyway, now that you have a function, you’d use the new statement to create a Person

This unit testing tip brought to you by Andy Murray: congrats Andy on winning your first grand slam title! The Problem Once you do test driven development at a scale that's beyond the smallest of projects, your test suite's runtime will inevitably grow. Best practices say that you should do everything in your power to keep the runtime low, because if it takes a long time to run your tests, chances

Let's say you want to intercept all calls to console.log, console.warn, and console.error, do something sneaky, and then proxy the call back to the original methods so that the messages get printed out as normal and no one ever has to notice. How would you do that? Attempt #1 If you are a seasoned Javascript programmer, you would probably go to monkeypatching and maybe write something like functio

I am a little framework averse. When I write a program, I like to build from scratch as far as it is practical. Not using a framework gives me the feeling that I am so in control of my own destiny. But having said that, I will sometimes succumb to using a framework when it's very clear that the use of the framework will result in significantly less code, and/or significantly less complexity I rece

About a week ago I released my Javascript test runner - Testem. It provides a text-based UI and auto-re-run-on-save for the test driven development(TDD) usecase as well as a simple command-line interface for continuous integration (CI). It supports QUnit, Jasmine, and Mocha to boot. To understand how the UI works, you really have to see it in action, I've made a screencast: There's also plenty of

Update: If you are using Jasmine 2.0 or above, the information here is out of date! Please go to http://jasmine.github.io/2.0/introduction.html#section-Spies instead. Wanna be a spy fast? Well you are in luck! Just kidding! This is actually a cheatsheet for Jasmine Spies. See, while Jasmine itself is very intuitive to use, every time use spies I have to look up the docs. I would blame it on the po