What are Comments?

Comments are notes in your code that the JavaScript engine ignores.
They help you explain what your code does, making it easier to read and maintain.

Single-Line Comments

Use // for short, single-line comments:

// This is a single-line comment
let age = 18;

Single-line comments are great for explaining a specific line.

Multi-Line Comments

Use /* */ for longer, multi-line comments:

/*
  This is a multi-line comment
  describing what happens below
*/
let name = "Shyam";

Multi-line comments are helpful for describing a block of code or a function's purpose.

Inline Comments

You can also place comments at the end of a line:

let price = 99; // store product price

These are good for clarifying small details.

Best Practices

Writing good comments makes your code easier to read and maintain. Keep these tips in mind:

• Keep comments concise and meaningful - Avoid restating obvious code, for example:

  let x = 10; // set x to 10

  Instead, use comments to explain why something is done or provide important context

• Clarify complex logic with comments - If the code is not immediately clear, add a comment to help future readers understand:

  // Check if the user is over 18 and has a valid ID
  if (age >= 18 && hasValidID) {
    // Allow access
  }

• Use consistent formatting - For example, start all comments with a capital letter.

• Keep comments up to date - If you change your code, remember to update the comments as well. Comments should describe the reason behind the code, not just what it does.

Example

// Calculate area of a circle
let radius = 5;
let area = Math.PI * radius * radius; // uses formula πr²

Comments like these help future you (or other developers) understand your thinking.