JavaScript Functions as JavaScript Variables

In Javascript instead of declaring and executing a function in two different steps.

for example

step 1 - 

function add(a,b){return a+b;}

step 2-

add(3,4);

result 7

Javascript provides an approach to declare and execute the function immediately. Which is known as IIFE(Immediately Invoked Function Expression)

Example:

(

function add(x,y){

alert(x+y);

})();