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The 10 Best JavaScript Development and Design Habits

JavaScript is an easy language to use, and a necessary one in today’s web. So much so that many developers come to JavaScript without any formal programming education. Hence, it’s not uncommon for developers to have years of JavaScript practice (or experimentation) under their belts without ever having established some best development and design habits. In this article, Larry Ullman outlines 10 guidelines that'll help every developer code more effectively.
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JavaScript is a very approachable language, one that forgoes the need for the daunting compilation or installation that comes with other languages like C, Java, PHP, or Ruby. Do a little bit of research online, slap together some code, and you can probably accomplish what you need to do. But to really excel with the language, to create reliable all-platform code, and to be able to develop code more rapidly, at some point you will need to adopt a few best practices.

In writing this article, I originally came up with a long list of suggestions, including some common and specific points such as not using the eval() function. After more thought, I was able to whittle the list down and structure them in the following 10 suggestions. A couple apply to all programming languages, some are very particular to JavaScript, and the last ones strive towards making you a better JavaScript developer[md]not just today, but as you head into the future. While the list is certainly not exhaustive, few seasoned programmers would argue with its recommendations.

Document Your Code!

Documenting your code is one of those things that all programmers (well, most) know they should do but few do well enough. Perhaps it’s because I’m a writer, but I think that proper code documentation is one of the most critical qualities. In order to do it right, you have to document your code while you write it, if not beforehand. Don’t make code documentation an afterthought! And don’t just add comments, but have them be thorough, useful, and above all, accurate.

Then, with JavaScript specifically, strip them all out (i.e., minify your code) in the versions of your scripts that will actually be distributed (be certain to save a non-minified copy for yourself).

Be Consistent

Some programmers get all worked up about the proper way to name variables or functions, or how control structures should be formatted. There are reasonable arguments to many different approaches and styles, but the only rule that’s absolute is to be consistent. Whatever styles, rules, and formatting you prefer, stick to those policies religiously. Doing so will reduce the number of trivial bugs and errors in your code, and make you a faster programmer.

Test/Handle Errors

Along with failing to properly document code, I find that many beginning programmers do a poor job of watching for and handling errors. It’s somewhat understandable: I know that when I start writing code, I want to get the project up and running as quickly as possible. Towards that end, the temptation is to implement the functionality based upon the web page, script, or application being used properly. But the amateur effort is differentiated from the professional one in how the application reacts when it’s not used properly. Never make assumptions in your code, and start watching for, and handling, errors from the get-go.

Master a Text Editor or IDE

Whether it’s a text editor or an Integrated Development Environment (IDE), you’ll use some sort of application to write your code. There are positives and negatives about each type, but choosing between a text editor and an IDE is largely a personal preference. On the other hand, there’s a strong argument to be made for being comfortable with one of each.

Regardless of what type of application you’re using, let alone which specific one, spend some time mastering it. The more you learn how to tap into your application’s capabilities and features, the faster you’ll be able to develop applications. And as most developers work with multiple languages and technologies, the time spent mastering your development tool will pay off many times over (assuming the same program can be used).

Master Firebug or Another Debugging Tool

On a similar note, you’ll want to make it a goal to master a debugging tool. It doesn’t matter if you master the tools built into a browser, an extension like the awesome Firebug, or something that comes with your IDE: Just find a debugger and become an expert in it!

With JavaScript, you’ll spend a lot of time debugging, so the investment in mastering a debugging tool will pay off quickly and repeatedly. To start, you’ll want to learn how to create breakpoints, including conditional breakpoints, so that you can follow the flow of logic and the values of variables as your code executes.

Validate Everything!

This suggestion is also related to debugging: Validate everything! Like being consistent when you program, validation doesn’t prevent all errors but will lessen the occurrence of the silly ones. When programming in JavaScript, you should start by validating your HTML and CSS, which is a good idea with web development in general.

Next, you can validate your JavaScript code using JSLint or JSHint. Doing so can catch potential errors and will secondarily enforce best practices.

Finally, you should validate the external data being used by your JavaScript code. For example, if your JavaScript retrieves XML or JSON from an Ajax call, syntactically invalid XML and JSON will make the result unusable. To nip that problem in the bud, insure that your server-side resources are returning valid XML or JSON by confirming, and validating, those results.

Use Today’s Development Approaches

Sometimes programming languages change not internally, in the language itself, but externally, as in how the language is used. This has very much been the case with JavaScript: How it was used in 1996 is vastly different than how it’s used today. The three most significant changes in JavaScript approaches are the adoption of:

  • Unobtrusive JavaScript
  • Object detection
  • Progressive enhancement

Entire articles have been written on each topic, but I’ll summarize them here. Unobtrusive JavaScript means that you should separate your JavaScript code from your HTML (15 years ago, JavaScript was frequently written inline, intermixed with the HTML). Taking an unobtrusive JavaScript approach results in code that’s cleaner and easier to maintain.

Object detection is the process of executing code based upon what the environment is capable of. By comparison, when I first started doing web development in the late 1990s, browser detection was commonly used: Identify the browser in use, and code according to what you know it can do. In today’s JavaScript, instead of looking at the browser type and version to know if it’s safe to do X or Y, simply directly test if X or Y is supported by the environment. For example, the String object added a new method named trim() in ECMAScript 5, but not all browsers have adopted it yet. To test if it’s safe to use this method, don’t look at the browser, look for the method:

if (typeof someStr.trim == 'function') { // Safe to use!

Finally, progressive enhancement is a modern alternative to the older approach of graceful degradation. Instead of writing the application to behave as you want it to and letting users know when they can’t use it (this is the graceful degradation model), start with the basic functionality that every user can take advantage of, regardless of his or her device, browser, or settings. Then progressively enhance the basic functionality by adding a layer of JavaScript that implements the desired dynamic behavior. Through this approach, people that can handle the enhanced JavaScript version will get it, while people who cannot will still be able to use your site. To determine into which camp the current user falls, use object detection!

Learn at Least Two Frameworks

The popularity and usability of JavaScript frameworks like jQuery has greatly expanded the popularity and usability of JavaScript itself. (The downside is that a number of developers erroneously think they can use a JavaScript framework without learning JavaScript in the first place.) In my opinion, it’s a mistake to assume that frameworks are the best solution to every problem, but often enough they are. You’ll only be able to make a good decision about whether or not to use a framework if you’re well versed in one. But I wouldn’t stop there: It behooves you to learn at least two frameworks so that you’re not using Framework X because it’s the only one you know.

Different frameworks have different strengths and weaknesses. You’ll be a much better developer, and create better websites, if you broaden your knowledge and are able to select the right tool for the job for each project. Furthermore, you’ll get a better appreciation for every framework you know when you add another one to your arsenal. In other words, when you go to learn that second framework, you’ll be able to see the first framework you learned in a new light.

Reduce, Reuse, and Recycle

Regardless of the language, if you spend any time programming, you’ll quickly develop frequently used bits of code that you’ve come to love and rely upon. You should embrace that natural tendency by formally turning the most atomic, useful chunks of code into your own personal modules or libraries that can be utilized by any JavaScript page you create. By doing so, you’ll develop projects much more quickly and reliably. In order to do this well, however, make the modules and libraries as narrow in scope and generic as possible, so that their usage and functionality is not coupled too tightly to any particular situation.

Continue to Learn

My final recommendation applies to everyone in all walks of life, in my opinion (not to be corny about it): Continue to keep learning. Especially when it comes to information technology, what you know today will be less and less valuable as time moves on. Stay current with emerging trends and new developments; read, read, read; and never stop learning as many new and various things as you can.


Whether you’ve been using JavaScript for years or weeks, have formal programming training or none whatsoever, I hope that this article has shown you a couple of best practices that you can embrace. Adopting the good skills put forth by this article, and honing them through hours of work, will benefit you many times over as you continue on as a developer.

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