Functions in Javascript

-A function is a reusable block of code that groups together a sequence of statements to perform a specific task.

-Function names can contain letters, digits, underscores, and dollar signs.

-JavaScript doesn't have a function data type but when we find the data type of a function using the type of operator, we find that it returns a function. This is because a function is an object in JavaScript. Ideally the data type of a function should return an object but instead, it returns a function.

SYNTAX:

                    function functionName(parameters) {

                                        //function body

                                        }

EXAMPLE:

OUTPUT:

In above, P1 and P2 are the parameters.

The code inside the {} is the function body and myFunction() is the function name.

 When JavaScript reaches a return statement, the function will stop executing.

Functions can be defined using:

FUNCTION DECLARATION:

Function declarations are built from:

The function keyword.

The function name.

An optional list of parameters separated by commas enclosed by a set of parentheses ().

 A function body enclosed in a set of curly braces {}.

EXAMPLE:

OUTPUT:

FUNCTION EXPRESSION:

Function expressions create functions inside an expression.

OUTPUT:

ARROW FUNCTION NOTATION:

It does not require 'function' keyword and uses a fat arrow '=>' separate the parameters from body.

Arrow functions with single parameter do not require () around parameters.

Arrow functions are always anonymous.

OUTPUT:

CONCISE ARROW NOTATION:

1.SINGLE-LINE BLOCK:

A single-line block function is a function that is written in a single line.

It returns the result of the expression following the arrow (=>).

It does not require the return keyword or curly braces {}.

OUTPUT:

2.MULTI-LINE BLOCK:

It can contain multiple statements within its body.

The body of the function is enclosed in curly braces {} and it requires an explicit return statement to return a value.

OUTPUT:

ANONYMOUS FUNCTION:

An anonymous function is a function without a name.

It can be defined using the function keyword followed by a set of parentheses () and curly braces {}, which contain the function’s code. 

Anonymous functions are often stored in variable or used as callbacks.

In anonymous function, we only use function keyword without function name.

EXAMPLE:

OUTPUT:

NAMED FUNCTION:

Functions with name or identifier are known as named functions.

Named functions are declared using the function keyword followed by name.

The function’s name is stored within its body.

EXAMPLE:

-Function without parameters:

OUTPUT:

-Function with parameters:

OUTPUT:

NESTED FUNCTION:

Nested function is Declaring function inside another function.

OUTPUT: