robertcoopercode

// Variable initialization
let x = 10; // x is given the number type

robertcoopercode

let anUndefinedVariable: undefined = undefined;
let aNullVariable: null = null; 

robertcoopercode

const darkestPlaceOnEarth = (): void => {
    console.log('Marianas Trench');
};

robertcoopercode

let whoKnows: any = 4; // assigned a number

whoKnows = 'a beautiful string'; // can be reassigned to a string
whoKnows = false; // can be reassigned to a boolean

robertcoopercode

enum Sizes {
    Small = 1,
    Medium,
    Large,
}

Sizes.Small; // => 1
Sizes.Medium; // => 2
Sizes.Large; // => 3

robertcoopercode

enum Sizes {
    Small,
    Medium,
    Large,
}

Sizes.Small; // => 0
Sizes.Medium; // => 1
Sizes.Large; // => 2

robertcoopercode

let myFavoriteTuple: [string, number, boolean];

myFavoriteTuple = ['chair', 20, true]; // ✅
myFavoriteTuple = [5, 20, true]; // ❌ - The first element should be a string, not a number

robertcoopercode

let myPetFamily: Array<string> = ['rocket', 'fluffly', 'harry'];

robertcoopercode

let myPetFamily: string[] = ['rocket', 'fluffly', 'harry'];

robertcoopercode

let decimalNumber: number = 42;
let binaryNumber: number = 0b101010; // => 42
let octalNumber: number = 0o52; // => 42
let hexadecimalNumber: number = 0x2a; // => 42