Functional vs.
Object-Oriented Programming
Object-Oriented
Uses self contained pieces of code, (classes in other OOP languages) in JavaScript, functions disguised as classes. Techniques used are Inheritance, Polymorphism, and Encapsulation.
Functional
Functional programming uses pure functions and avoids side effects, meaning if you put the same input in, you will always get the same output.
OOP Example
function User(name, email){
this.name = name;
this.email = email;
}
User.prototype.greeting = function(){
return `Hi I am ${this.name}.
Please email me at ${this.emeil}`
}
class User{
constructor(name, email){
this.name = name
this.email = email
}
greeting(){
return `Hi I am ${this.name}.
Please email me at ${this.emeil}`
}
}
const jon = new User('jon', 'jon@me.com')Functional Example
function createUser(name, email){
const obj = {}
obj.name = name;
obj.email = email;
obj.greeting = function(){
return `Hi I am ${this.name.
Please email me at ${this.email}}`
}
}
let jon = createUser('jon', 'jon@me.com')
OOP uses
Imperative Pattern
What is Imperative pattern?
Imperative Pattern focuses on describing how a program operates. It has commands for the computer to perform.
let books = [
{name:'JavaScript', pages:450},
{name:'Angular', pages:902},
{name:'Node', pages:732}
];
for (var i = 0; i < books.length; i++) {
books[i].lastRead = new Date();
}Example:
Functional uses
Declarative Pattern
Declarative pattern?
Declarative Pattern focuses on what the program should accomplish without specifying how the program should achieve the result.
let books = [
{name:'JavaScript', pages:450},
{name:'Angular', pages:902},
{name:'Node', pages:732}
];
let newBooks = books.map((book)=> {
book.lastRead = new Date()
return book;
});
Example:
Great Resource
(oldie but a goodie)
Master the JavaScript Interview: What is Functional Programming?
Functional Programming
By JD Richards
