Comments

C# and TypeScript/JavaScript use the same basic comment syntax: // for single-line comments and /* */ for multi-line comments. However, C# introduces XML documentation comments, written with ///, which integrate with tools like IntelliSense and generate API documentation (/// <summary>Describes a method</summary>). TypeScript supports JSDoc-style comments (/** ... */), which provide similar documentation capabilities but rely on external tooling rather than built-in language support.

Unlike JavaScript, where comments are purely for human readability, C#'s XML comments can enforce structured documentation and provide compile-time feedback. While both languages encourage clear commenting practices, C#’s built-in documentation system makes it easier to maintain well-documented code, especially for large projects and libraries.

Inline

// Single line
if (x == y) { }

if (x == y) { } // Single line

// Single line
if (x == y) { }

if (x == y) { } // Single line

Block

/*
Block comment
*/
if (a == b) { }

if (a == b) { /* Inline block comment */ }

/*
Block comment
*/
if (a == b) { }

if (a == b) { /* Inline block comment */ }

Class and Function

/**
 * Adds two numbers
 * @param a First number
 * @param b Second number
 * @returns The sum of a and b
 */
function sum(a: number, b: number) : number { }

/// <summary>
/// Adds two numbers
/// </summary>
/// <param name="a">First number</param>
/// <param name="b">Second number</param>
/// <returns>The sum of a and b</returns>
int Sum(int a, int b) { }

WARNING

Because C# comments are XML, they cannot contain <, >, &, and a few other XML entities. Use <, >, or & if you must. But generally, consider alternative ways of representation.

TIP

It is very tedious to type out the XML! So get an extension for your IDE that does it automatically when you type ///.