Functions

Functions are reusable blocks of code designed to perform a specific task. They help organize code, avoid repetition, and improve readability.

Basic Syntax

A function is defined using the function keyword, followed by a name, parentheses for parameters, and a block of code:

function greet() {
  console.log("Hello, world!");
}
greet();

Function Parameters and Arguments

Functions can accept inputs called parameters. When you call the function, you provide arguments to fill those parameters.

function greet(name) {
  console.log("Hello, " + name + "!");
}
greet("Alice");
greet("Bob");

Return Values

Functions can return a value using the return statement. This allows the function to output a result that can be stored or used elsewhere.

function add(a, b) {
  return a + b;
}
const sum = add(5, 3);
console.log(sum);

Function Expressions

Functions can also be stored in variables. These are called function expressions.

const multiply = function(x, y) {
  return x * y;
};
console.log(multiply(4, 6));

Arrow Functions (ES6+)

A concise syntax for function expressions, especially useful for simple functions.

const square = n => n * n;
console.log(square(5));