JS Coding Conventions

Coding conventions are style guidelines for programming.

They typically cover:

  • Naming and declaration rules for variables and functions.
  • Rules for the use of white space, indentation, and comments.
  • Programming practices and principles

Coding conventions secure quality:

  • Improves code readability
  • Make code maintenance easier

General JavaScript code conventions used by W3Schools:

  1. Variable And Function Names
    • camelCase
    • start with a letter
    • Global variables & Constants written in UPPERCASE
    • Hyphens are not allowed in JavaScript names.
  2. Spaces Around Operators
  3. Code Indentation
    • Always use 4 spaces
    • Do not use tabs (tabulators) for indentation. Different editors interpret tabs differently.
  4. Always end a simple statement with a semicolon
  5. General rules for complex (compound) statements:
    • Put the opening bracket at the end of the first line.
    • Use one space before the opening bracket.
    • Put the closing bracket on a new line, without leading spaces.
    • Do not end a complex statement with a semicolon.
    • EX:
      if (time < 20) {
       greeting = "Good day";
  6. Line Length
    • if tool long, break it after an operator or a comma.

Use Lower Case File Names

  • Most web servers (Apache, Unix) are case sensitive about file names:
    • EX: london.jpg cannot be accessed as London.jpg.
  • Other web servers (Microsoft, IIS) are not case sensitive:
    • EX: london.jpg can be accessed as London.jpg or london.jpg.
  • Always use lower case file names (if possible).


  • Coding conventions are not used by computers. Most rules have little impact on the execution of programs.
  • Indentation and extra spaces are not significant in small scripts.
  • For code in development, readability should be preferred. Larger production scripts should be minified.

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