JavaScript Functions

JavaScript functions are an essential part of the language, allowing you to define reusable blocks of code. Functions can help you organize your code, make it more readable, and maintainable.

Basic Syntax

The basic syntax for a JavaScript function is as follows:

function functionName(parameters) {
  // code to be executed
}

Types of Functions

There are two types of functions in JavaScript:

Built-in Functions: These are functions that are provided by JavaScript itself. Examples include alert(), parseInt(), and Math.random().
User-Defined Functions: These are functions that you create yourself. They can be used to perform specific tasks that are not provided by built-in functions.

Example

Here is an example of a user-defined function that calculates the sum of two numbers:

function addNumbers(a, b) {
  return a + b;
}

console.log(addNumbers(5, 3)); // Outputs: 8

Parameters and Arguments

Functions can accept parameters, which are values passed into the function. These parameters are defined in the function's parentheses.

function greet(name) {
  console.log('Hello, ' + name + '!');
}

greet('Alice'); // Outputs: Hello, Alice!

In the above example, name is a parameter. When we call greet('Alice'), Alice is passed as an argument.

Return Values

Functions can also return values. The return statement is used to specify the value that the function should return.

function multiply(a, b) {
  return a * b;
}

console.log(multiply(4, 3)); // Outputs: 12

Arrow Functions

Arrow functions are a newer addition to JavaScript. They provide a more concise syntax for writing functions.

const greet = (name) => {
  console.log('Hello, ' + name + '!');
};

greet('Bob'); // Outputs: Hello, Bob!