Course source code: https://codistwa.com/guides/variables-and-types. More courses on https://codistwa.com

variables.js

// ============================================================
// Definition of a variable
// ============================================================

const welcome = 'Hello';
console.log(typeof(welcome)); // string

// ============================================================
// Types
// ============================================================

const welcome = 'Hello';
let length = 2;
const isHidden = false;

// ============================================================
// Concatenation
// ============================================================

const presentation = 'I have';
let age = 32;

console.log(presentation + ' ' + age); // I have 32
console.log(`${presentation} ${age}`); // I have 32

// ============================================================
// Mutation
// ============================================================

const welcome = 'Hello';
let length = 2;

welcome = 't';
length = 3;

console.log(welcome); // error
console.log(length); // no error

// ============================================================
// Conversion
// ============================================================

console.log('3' + 2); // 32
console.log('3' - 2); // 1
console.log('five' * 2); // NaN

// ============================================================
// Scope
// ============================================================

const doors = 5; // global

function getDoors() {
  const bathrooms = 1; // local
  console.log(doors);
}

function getBathRooms() {
  console.log(bathroom); // error
}

console.log(getDoors()); // 5
console.log(getBathRooms()); // undefined

// ============================================================
// Naming conventions
// ============================================================

// bad
const str = 'Marie';
// good
const firstName = 'Marie';

// bad 
const zero = 0;

// good
const total = 0;

// bad
const open = true;
const hidden = false;

// good
const isOpen = true;
const isHidden = false;

variables.py

# ============================================================
# Definition of a variable
# ============================================================

welcome = 'Hello'
print(type(welcome))  # <class 'str'>

# ============================================================
# Types
# ============================================================

welcome = 'Hello'
length = 2
isHidden = False

# ============================================================
# Concatenation
# ============================================================

presentation = 'I have'
age = 32

print(presentation + ' ' + str(age))  # I have 32
print("%s %s" % (presentation, str(age)))  # I have 32

# ============================================================
# Mutation
# ============================================================

length = 2
length = 3

print(length)  # 3

# ============================================================
# Conversion
# ============================================================

print('3' + str(2))  # 32
print('five' * str(2))  # Error

# ============================================================
# Scope
# ============================================================

doors = 5  # global


def getDoors():
    bathrooms = 1  # local
    print(doors)


def getBathRooms():
    print(bathroom)  # error


print((getDoors()))  # 5
print(getBathRooms())  # None

# ============================================================
# Naming conventions
# ============================================================

# bad
str = 'Marie'
# good
first_name = 'Marie'

# bad
zero = 0

# good
total = 0

# bad
open = True
hidden = False

# good
is_open = True
is_hidden = False