JavaScript functions

JavaScript functions are one of the building blocks of the language and are used to perform a specific task or calculation. Functions are reusable blocks of code that can be called multiple times with different inputs. Function will act as a reusable code block to use again as needed.

A function in JavaScript is defined using the function keyword followed by a function name, a list of parameters enclosed in parentheses, and the function body enclosed in curly braces. Here's an example of a simple function that adds two numbers:

1function add(num1, num2) {
2  return num1 + num2;
3}

To call the function, we simply use its name followed by the arguments in parentheses:

1let result = add(3, 2);
2console.log(result); // 5

Functions in JavaScript can also have optional parameters, which can be specified using default values in the function definition. For example:

1function greet(name = "Max") {
2  console.log("Hello, " + name);
3}
4
5greet("Kim"); // Hello, Kim
6greet(); // Hello, Max

Another powerful feature of JavaScript functions is the ability to return a value. The return statement is used to specify the value that the function should return. For example:

1function square(x) {
2  return x * x;
3}
4
5let result = square(5);
6console.log(result); // 25

In addition to named functions, JavaScript also supports anonymous functions, which are functions without a name. Anonymous functions are often used as arguments for other functions or as immediately-invoked function expressions (IIFEs).

1(function () {
2  console.log("Hello from an anonymous function!");
3})();

Functions in JavaScript are a powerful tool that allow us to encapsulate and reuse logic, making our code more modular and maintainable. They are an essential aspect of the language and are used in a wide range of applications.