JavaScript Comments

Comments are used to explain code and make it more readable. They can also be used to prevent execution when testing alternative code.

1. Single-line Comments

Single-line comments start with //. Any text between // and the end of the line is ignored by JavaScript (will not be executed).

// This is a single-line comment
var x = 5; // This is another single-line comment

2. Multi-line Comments

Multi-line comments start with /* and end with */. Any text between /* and */ will be ignored by JavaScript.

/*
This is a multi-line comment
It spans multiple lines
*/
var y = 10;

/* This is another multi-line comment
   that starts and ends on the same line */
var z = 15;

3. Using Comments for Debugging

Comments are often used to temporarily disable code for debugging purposes.

var total = 0;
// total = total + 1;
total = total + 5;
console.log(total); // Output will be 5

4. Best Practices for Comments

Good comments explain “why” something is done, not “what” is done. The code itself should be self-explanatory as to “what” is done.

Here are some tips for writing good comments:

• Keep comments concise and to the point.
• Update comments if you update your code.
• Use comments to explain complex logic.

// Calculate the factorial of a number
function factorial(n) {
    // If n is 0, its factorial is 1
    if (n === 0) {
        return 1;
    }
    // Otherwise, recursively calculate the factorial
    return n * factorial(n - 1);
}

By following these guidelines, you can make your code more understandable and maintainable.