Functions are one of the most important concepts in JavaScript. They allow you to group together related code and make it reusable.
A function is a block of code that is executed when it is called. Functions can take in parameters and return values.
To define a function in JavaScript, you use the function keyword. The syntax is as follows:
function functionName(parameters) {
// Body of the function
}
The functionName is the name of the function. The parameters are the values that the function takes in. The Body of the function is the code that is executed when the function is called.
To call a function, you use the function name followed by the parentheses. The parentheses can contain the parameters, but they are not required.
For example, the following function defines a function called factorial() that takes in a number as a parameter and returns the factorial of that number:
function factorial(n) {
if (n == 0) {
return 1;
} else {
return n * factorial(n - 1);
