How to Better Name Your Functions and Variables

We all know the struggle of naming things. Sometimes a perfect name arrives in seconds; sometimes you spend an hour and settle for tmp or value. Next time it comes up, keep a few simple ideas in mind — you will write more readable code and make it easier for the next person, including your future self.

Functions, variables, and classes all follow the same principle. Think of a name as a tiny comment.

Pack information into names.

Choose a word with meaning

Pick a specific word and avoid empty ones. Imagine an API that returns books:

function get(url) { ... }

get says almost nothing. What are we getting, and from where?

function getBooks(url) { ... }

Better. And if the source matters:

function fetchBooks(url) { ... }
// or, when you have several services
function getBooksFromAPI(url) { ... }

It's better to be clear and precise than to be cute.

Think about what the function actually does or what the variable holds — but don't overthink it.

Avoid generic names

tmp, x, a, obj, foo are usually synonyms for "I don't know how to name this." Sometimes generic is fine:

if (right > left) {
  const tmp = right
  right = left
  left = tmp
}

Here tmp is exactly right — short-lived temporary storage is the most important fact about it. But not here:

let tmp = user.firstName()
tmp += ' ' + user.lastName()
return tmp

fullName carries more meaning. Loop counters i, j, k are understood, but nested loops read better as c for classes and s for students.

If you're going to use a generic name like tmp, it, or retval, have a good reason for doing so.

Attach additional information

Any extra information you squeeze into a name can have a big impact on readability. Add units:

const startMs = Date.now()
// ...many lines below...
const elapsedMs = Date.now() - startMs

Do this any time there is something dangerous or surprising about the value. When handling sensitive data, plainPassword and hashedPassword beat a bare password. Reserve this for places where a bug can sneak in from someone using a value the wrong way.

Make the name the right size

Too long is hard to read and remember:

newNavigationControllerWrappingViewControllerForDataSourceOfClass()

Shorter names are okay for shorter scope.

function checkPassword(password) {
  const s = password.length
  if (s < 8) {
    // ...
  }
}

s is fine in a tiny scope. If the function grew complex, it would lose its meaning. Beware abbreviations too — BEManager saves keystrokes over BackendManager but can confuse a new teammate.

Consistent formatting

Capitalization and underscores carry information: an initial capital often marks a class, all-caps marks a constant, a leading or trailing underscore often means private. The main goal is consistency — pick a convention and stick to it.

Summary

Pack information into your names.

The reader should be able to extract as much as possible from the name alone.

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Originally published on Medium.