Functions in JavaScript.

In JavaScript, we write code to perform a specific task or to achieve something. In Javascript, we have functions to perform a specific task. function is nothing but a block of code that performs a particular task. A function is executed when something calls it and a function is composed of statements called function body.

Syntax

function sum () {
//function body
}

A Javascript function is defined with a function keyword, followed by a name, and followed by a parenthesis (). Function names can contain digits, letters, signs, etc., and parenthesis contains parameter names separated by commas.

we have declared a function named message(). To use a function, we have to call it.

Example

function add () {
let x = 12;
let y = 12;
let z = x + y;
console.log(z);
}
add();

Parameters and Arguments

The value which we pass inside a function is known as an argument and a parameter is a value that is passed when declaring a function.

Example

function add (x, y) {
let z = x + y;
console.log(z);
}
add(12, 12);

Ways to write the function

function user () {
let first_Name = 'vikas';
console.log(first_Name);
}
user();

var user = function () {
let first_Name = "vikas";
console.log(first_Name);
}
user();

var user = () => {
let name = "vikas";
}
user();

Function statement/Declaration

function call () {
console.log("ineuron");
}

Function expression

let call = function () {
console.log("ineuron");
}

here storing function into call and function can also be defined as expressions

Function with return

The return statement can be used to return the value to a function call. It denotes that the function has ended. Any code after the return is not executed and nothing is returned the function returned an undefined value.

Example

function sum (math, physics, chemistry) {
var result = math + physics + chemistry;
return result;
}
let total = sum (74, 84, 92);
console.log(total);