Case

Use camelCase when naming variables and functions

When a function is intended to be called as a constructor function (i.e. with the new keyword), use the PascalCase instead. Pascal case is simply camel case, except that the first letter is capitalised.

Javascript is quite relaxed in which characters it allows in legal variable or function names, use instead what would be normal variable naming conventions other C-style syntax languages:

  • First character can be an alphabet (upper case or lower case)
  • Second and subsequent characters can be a digit or an alphabet (upper case or lower case)
  • Avoid using _, $, \
  • Avoid any characters with an ASCII code of over 127
  • Avoid all Unicode characters

Abbreviations

With the exception of temporary variables, such as the occasional i and j that you might use as the iterator index in a for loop, avoid abbreviating or otherwise obfuscating your variable and function names.

Spell them out in full! After all, abbreviations are the job for a minifier, which will minimise the length of all of your Javascript variables anyway!

function a(b) {
  return b.last || bar.first;
}

What is a? What is b? If you were to look at this in three months time, would you not wish that you had written this instead?

function selectDefaultName(person) {
  return person.last || person.first;
}

In the same vein, avoid giving ambiguous names to variables:

  • Instead of pos, call it boxPosition
  • Instead of num, call it numBoxes

Prefixes and Suffixes

Avoid prefixing or suffixing variables names with the types that they contain.

  • Instead of studentArray or studentArr, simply use students instead.
  • Instead of objWallet or walletObj, simply use wallet instead.

Project level consistency

There are a number of other naming conventions that you may choose to adopt, that may not be applicable across different projects. However, it always makes sense to ensure consistency within an entire project.

For example, because Javascript does not natively support the concept of private variables, or support the concept of constants, many developers adopt conventions such as:

  • Private variables’ names must be preceded with _
  • Constants’ names must be is ALL_CAPS

These additional naming conventions are not necessary, but can be beneficial to adopt across the entire project, in addition to the ones described here.