Popular posts

FP is a supreme paradigm and very simple. OOP is based on functional. Think about it like math in school where you got simple functions like f(x), y = 5 + 10x, etc.

Main aspects of FP

1. Single responsibiloty principle, each function is minimal and do only one thing.

2. Pure functions:

   2.1. same function call with same arguments always will return same result,

   2.2. no side effects - function does not depends on time, weather and does not change anything outside of it

3. because of that - very easy to test and write, system is more stable and predictable, easy to maintain, change, replace functions.
4. closures,
5. composition - functions returning functions, which allows to write a little of reusable code
6. recursion - functions calling itself
7. simple - no complexity and huge class hierarchies at all like in OOP
8. helps thinking, less useless abstraction

---

1. Difference between OOP and FP

// OOP
class Model {
    ...
}

class User extends Model {
    getName() { return this.name }
    setName(name) { this.name = name }
}

// FP
function model(table, id) {
    return sql_array('SELECT * FROM ? WHERE id = ?', [table, id]);
}

function user(id) {
    return model('users', id);
}

2. What languages support it?

Actually very many. C, Python, Lua, C#, Haskell, Perl, Erlang, Elixir, JavaScript, PHP, ...

3. Does JavaScript supports FP?

JavaScript is primarily a functional language, same with PHP

4. Should you be worried about not knowing it?

Yes, you should, and a lot.

5. Where you can get started to learn basics of Functional programming in JavaScript

• Good presentation from SoundCloud why they reject the most JS applications.

• Another interesting slide on Fun with Functions.

• Read/watch/follow Eric Elliott, JS architect writting modern articles about JS and FP.

• The Two Pillars of JavaScript — Pt 2: Functional Programming.

• Master the JavaScript Interview: What is a Pure Function?