Functions in JavaScript: User-Defined and Standard Library Functions

What is a Function?

A function is a reusable block of code designed to perform a specific task, which can be called whenever needed.

Standard (Built-in) Functions

JavaScript provides many built-in functions like parseInt(), isNaN(), Array.isArray(), and object methods like Math.max().

User-Defined Functions

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

Function Expressions

const add = function(a, b) {
    return a + b;
};