JS has 1st Class Functions

first_class_function.js

/**
 * Why we call javascript as a first class functions
 */

// Create a function
var square = function(x){
   return x*x;
};

// Return a function 
var mult = function(f1, f2){
   return function(n){
      return f1(n) * f2(n);
   }
};

//Arguments can be passed as functions.
var bigF = mult(square, square);

//Default and other languages supports i.e calling a function
var value = bigF(2);