# Variables

_const_ - Constant, can't be changed

``` javascript
const tickets = 3;

// tickets === 3
```

_let_ - Temporary, can be changed

``` javascript
let tickets = 3;

let tickets = tickets - 1;  // somebody purchases a ticket

// tickets === 2
```

# Primitives

_boolean_ - true / false

``` javascript
const hasRemainingTickets = true;

// if we have tickets remaining

if (hasRemainingTickets === true) {
  purchaseTickets(1);  // purchase 1 ticket
}
```

_number_ - any number positive or negative

``` javascript
// whole numbers
const positiveNumber = 13;
const negativeNumber = -42;

// float numbers
const floatNumber = 4.43;
const negativeFloatNumber = -9.75;
```

_string_ - any combination of characters or number

``` javascript
// characters only
const firstName = 'Lance';
const fullName = 'Lance Jernigan';

// characters and numbers
const username = 'Pineapple17';
const password = 'Y21@EUVK9Ur1H!';
```

_null_ - intentionally empty

``` javascript
const paddleBoats = null;

// We don't sale paddleBoats but we could
```

_undefined_ - exists but doesn't have a value

``` javascript
let tickets;

if (tickets === undefined) {
  let tickets = 0;

  // we should make sure there's a numerical value
}
```

# Objects

_object_ - represents a data structure

``` javascript
const user = {
  firstName: 'Lance',
  lastName: 'Jernigan',
  phone: '8653041322',
  email: 'lance.t.jernigan@gmail.com',
  userId: 3,
}
```

_array_ - a list of items

``` javascript
// numbers
const primesLessThan10 = [ 1, 3, 5, 7 ];

// strings
const shows = [
  'Fantastic Beasts: The Crimes of Grindelwald',
  'Bohemian Rhapsody',
  'The Grinch',
];

//objects
const tickets = [
  {
    type: 'adult',
    price: 12.35,
  },
  {
    type: 'child',
    price: 9.75,
  }
]
```

_function_ - an action

``` javascript
let tickets = 3;

const purchaseOneTicket = () => {
  let tickets = tickets - 1;  // subtract 1 from tickets
}

purchaseOneTicket();
```

Functions can return any value

``` javascript
const subtract = (a, b) => {
  // a = 3
  // b = 1

  return a - b;  // 3 - 1 = 2
}

const tickets = subtract(3, 1);

// tickets === 2;
```