javascript

Chapter 20: Best Practices
What Is Maintainable Code?
Maintainable code has several characteristics. In general, code is said to be maintainable when it is all of
the following:
❑
❑
❑
❑
❑
Understandable — Someone else can pick up the code and figure out its purpose and general
approach without a walkthrough by the original developer.
Intuitive — Things in the code just seem to make sense, no matter how complex the operation.
Adaptable — The code is written in such a way that variances in data don ’ t require a complete
rewrite.
Extendable — Care has been given in the code architecture to allow extension of the core
functionality in the future.
Debuggable — When something goes wrong, the code gives you enough information to
identify the issue as directly as possible.
Being able to write maintainable JavaScript code is an important skill for professionals. This is the
difference between hobbyists who hack together a site over the weekend and professional developers
who really know their craft.
Code Conventions
One of the simplest ways to start writing maintainable code is to come up with code conventions for the
JavaScript that you write. Code conventions have been developed for most programming languages, and
a quick Internet search is likely to turn up thousands of documents. Professional organizations have long
instituted code conventions for developers in an attempt to make code more maintainable for everyone.
The best - run open - source projects have strict code convention requirements that allow everyone in the
community to easily understand how code is organized.
Code conventions are important for JavaScript because of its adaptability. Unlike most object - oriented
languages, JavaScript doesn ’ t force developers into defining everything as objects. The language can
support any number of programming styles, from traditional object - oriented approaches to declarative
approaches to functional approaches. A quick review of several open - source JavaScript libraries can
easily yield multiple approaches to creating objects, defining methods, and managing the environment.
The following sections discuss the generalities of how to develop code conventions. These topics are
important to address, although the way in which they are addressed may differ, depending on your
individual needs.
Readability
For code to be maintainable, it must first be readable. Readability has to do with the way the code is
formatted as a text file. A large part of readability has to do with the indentation of the code. When
everyone is using the same indentation scheme, code across an entire project becomes much easier to
read. Indentation is usually done by using a number of spaces instead of by using the tab character,
which is typically displayed differently by different text editors. A good general indentation size is four
spaces, although you may decide to use less or more.
636