Variable Naming Best Practices in JavaScript
TLDR: Well-chosen variable names significantly improve the readability and maintainability of JavaScript code. Adopting modern conventions like let and const, using meaningful names, and following naming patterns such as camel case and uppercase constants help maintain cleaner, more structured code. Avoid abbreviations, single-letter variables, and combine good practices to ensure clarity.
1. Avoid var: Outdated and Unpredictable
Prior to ES6, var was used to declare variables, but it introduced unpredictable behavior due to function-level scoping. Modern JavaScript uses let and const for block-scoped, more manageable variables, reducing bugs and increasing code clarity.
// Use let and const instead of var
let age = 25;
const name = 'John';
2. Use let for Reassignable Variables
let should be used when the variable’s value may change later in the code.
let count = 0;
count++;
3. Use const for Constants
For values that remain unchanged throughout the code, use const. This ensures consistency and prevents accidental reassignment.
const TAX_RATE = 0.15;
4. Clear and Descriptive Naming
Variable names should be self-explanatory, indicating their purpose. Avoid unclear, ambiguous names.
// Good
let firstName = 'Alice';
let totalPrice = 50;
// Bad
let x = 'Alice';
let temp = 50;
5. Avoid Abbreviations
Names should be written out clearly to avoid confusion, especially when working with other developers.
// Good
let customerName = 'Alice';
// Bad
let custNm = 'Alice';
6. Use Camel Case
Camel case is widely adopted in JavaScript for variable names, where the first word is lowercase and subsequent words are capitalized.
// Good
let fullName = 'John Doe';
// Bad
let full_name = 'John Doe';
7. Uppercase for Constants
Constants that remain unchanged should be written in uppercase, with words separated by underscores.
// Good
const MAX_ATTEMPTS = 3;
// Bad
const maxAttempts = 3;
8. Avoid Single-Letter Variables
Single-letter variables generally decrease readability. Use descriptive names, except in specific cases like loop counters.
// Good
let counter = 0;
// Bad
let i = 0;
9. Use Plurals for Arrays
When naming arrays, use plural forms to indicate that the variable holds multiple values.
// Good
let productNames = ['Item1', 'Item2'];
// Bad
let productName = ['Item1', 'Item2'];
10. Prefix Boolean Variables
Boolean variables should start with prefixes like is, has, or can to clearly indicate their purpose.
// Good
let isActive = true;
let hasDiscount = false;
// Bad
let active = true;
let discountApplied = false;
11. Scope-Aware Naming
When dealing with scoped variables, indicate the scope in the name to differentiate them from global variables.
// Good
let globalCounter = 100;
let localIndex = 5;
// Bad
let counter = 100;
let index = 5;
12. Declare Variables Separately
For readability, declare variables one by one, rather than bundling multiple declarations into a single line.
// Good
let isActive = true;
let canEdit = false;
// Bad
let isActive = true,
canEdit = false;
Following these practices leads to cleaner, more predictable code, making collaboration and long-term maintenance easier.