10 First Class Functions .js

a();//It will call the function a
// b();//It will throw an error undefined

//Function Expression
//also called as function declaration
function a() {
    console.log("a called");
}
//a()//you can call it from here 

//Function Declaration
var b = function () {
    console.log("b called");
}
b()//you can only call it after the function

//Anonymous function
// function () {

// }

// Named function expression
var b = function xyz() {
    console.log(xyz);
}
b()
xyz()//you cannot call this function using xyz due to its scope properties //error undefined

// Differnce between parameter and arguements
param1 = 10;
param2 = 20;
var b = function (param1, param2) {// the value passed here are called as parameters 
    console.log("b called");
}
b(param1, param2)// the value passed here are called as arguements

//First class function
//abilities to use functions as values is called as first class function
var b = function (param1) {
    return function xyz() {

    }
}
console.log(b())//we can return function in function as arguement