Functions in JavaScript

 

In JavaScript, a function is a block of code that can be defined once and executed repeatedly. Functions in JavaScript can be defined using the function keyword followed by a name and a set of parentheses, which can optionally contain one or more parameters. The function body is then enclosed in curly braces. Here is an example of a basic function that takes two parameters and returns their sum:

javascript

function addNumbers(num1, num2) {
  return num1 + num2;
}

Once a function is defined, it can be called by its name followed by a set of parentheses containing any necessary arguments. Here is an example of calling the addNumbers function with the arguments 2 and 3:

javascript

let sum = addNumbers(2, 3);
console.log(sum); // Outputs 5

In addition to regular functions, JavaScript also supports anonymous functions (also known as lambda functions) which can be defined without a name and assigned to a variable. Here is an example of an anonymous function that takes a single parameter and returns its square:

javascript

let square = function(num) {
  return num * num;
};

let result = square(5);
console.log(result); // Outputs 25

JavaScript also supports arrow functions, which provide a more concise syntax for defining anonymous functions. Here is an example of an arrow function that takes a single parameter and returns its square:

javascript

let square = (num) => num * num;

let result = square(5);
console.log(result); // Outputs 25