Function Expression and Anonymous Function in javascript

JavaScript allows us to assign a function to a variable and then use that variable as a function. It is called function expression.

Example: Function expression

var Subtraction = function sub(val1, val2) {

    return val1 - val2;

};

var result1 = Subtraction (10,20);

var result2 = sub(10,20); // not valid

JavaScript allows us to define a function without any name. This unnamed function is called anonymous function. Anonymous function must be assigned to a variable.

Example: Anonymous Function

var showMessageSample = function (){

    alert("Welcome to javascript function!");

};

showMessage();

var sayHi = function (firstName) {

    alert("Hello " + firstName);

};

showMessageSample ();

sayHi("Javascript");