Learning typescript

play.ts

// Typescript Documentation:
// https://www.typescriptlang.org/docs/

// Basic Types
const message: string = "Hello world";
const messageArr: Array<string> = [message];
console.log(message);
console.log(messageArr);

const isValid: boolean = false;
const isValidArr: Array<boolean> = [isValid];
console.log(isValid);
console.log(isValidArr);

const noOfSocks: number = 3;
const noOfSocksArr: Array<number> = [noOfSocks];
console.log(noOfSocks);
console.log(noOfSocksArr);

const x: [string, number] = ["Foo", 100];
console.log(x);

const [y, z]: [string, number] = ["Foo", 100];
console.log(y, z);

const { a, b }: { a: string; b: number } = { a: "Wind", b: 800 };
console.log(a, b);

const obj: Object = { name: "Foo Bar", age: 33 };
console.log(obj);

const arr: Array<any> = [1, 3, "100"];
console.log(arr);

const test = (): number => {
  console.log("This is test function!");
  return 0;
};
test();

const partial = (): Function => {
  return (): Array<number> => {
    return [1, 100];
  };
};
console.log(partial()());

// Interfaces
interface Label {
  label: string;
}
const printLabel = (labelObj: Label) => console.log(labelObj.label);
printLabel({ label: "This is a label!" });

interface User {
  readonly id: string;
  email: string;
  phone?: string;
}

const u: User = {
  id: "ERTYU234",
  email: "support@example.com",
  phone: "9876543210"
};
u.email = "care@example.com";
console.log(u);

interface SumType {
  (a: number, b: number): number;
}

const add: SumType = (x, y) => x + y;
console.log(add(2, 10));

interface ClockInterface {
  currentTime: Date;
  setTime(d: Date): void;
}

class Clock implements ClockInterface {
  currentTime: Date = new Date();
  setTime(d: Date) {
    this.currentTime = d;
  }
  constructor(public hours: number, private mins: number) {}
}

const c = new Clock(10, 20);
console.log(c);

// Classes
class Animal {
  name: string;
  constructor(theName: string) {
    this.name = theName;
    console.log("Hey this is Animal constructor.");
  }
  move(distanceInMeters: number = 0) {
    console.log(`${this.name} moved ${distanceInMeters}m.`);
  }
}

class Snake extends Animal {
  move(distanceInMeters = 5) {
    console.log("Slithering...");
    super.move(distanceInMeters);
  }
}

class Horse extends Animal {
  move(distanceInMeters = 45) {
    console.log("Galloping...");
    super.move(distanceInMeters);
  }
}

const sam = new Snake("Sammy the Python");
const tom: Animal = new Horse("Tommy the Palomino");

sam.move();
tom.move(34);

class Bottle {
  public company: string;
  protected price: string;
  private manufacturedAt: string;

  constructor(company: string, price: string, manufacturedAt: string) {
    this.company = company;
    this.price = price;
    this.manufacturedAt = manufacturedAt;
  }

  info() {
    console.log("The bottle is manufactured at " + this.manufacturedAt);
  }
}

const k = new Bottle("Kinley", "20", "Kanpur");
console.log(k);
k.info();

class Octopus {
  readonly name: string;
  readonly numberOfLegs: number = 8;
  constructor(theName: string) {
    this.name = theName;
  }
}

const oswald = new Octopus("Man with the 8 strong legs");
console.log(oswald);

class Employee {
  static MAX_FULL_LENGTH: number = 10;
  private x: string = "";

  get fullName(): string {
    return this.x;
  }

  set fullName(newName: string) {
    if (newName && newName.length > Employee.MAX_FULL_LENGTH) {
      throw new Error(
        "fullName has a max length of " + Employee.MAX_FULL_LENGTH
      );
    }

    this.x = newName;
  }
}

const employee = new Employee();

employee.fullName = "Bob Smith";
console.log(employee.fullName);

// Functions
const sayHello = ({ name }: { name: string; age?: number }): void =>
  console.log("Hello " + name);
sayHello({ name: "Joe" });

const sayHi = (person: { name: string; age?: number }): void =>
  console.log("Hi " + person.name);
sayHi({ name: "Joe" });

type Person = { name: string; age?: number };
const greet = (person: Person): void =>
  console.log("Good morning " + person.name);
greet({ name: "Joe" });

interface Human {
  name: string;
  age?: number;
}
const wish = (human: Human): void =>
  console.log("Happy Birthday " + human.name);
wish({ name: "Joe" });

const buildName = (firstName: string, ...restOfName: Array<string>) => {
  return firstName + " " + restOfName.join(" ");
};

const employeeName = buildName("Joseph", "Samuel", "Lucas", "MacKinzie");
console.log(employeeName);

// Generics
const identity = <R>(a: R): R => a;
console.log(identity<string>("Hello!"));
console.log(identity<Array<number>>([1, 8, 10]));

const getLength = <T>(a: Array<T>): number => {
  return a.length;
};
console.log(getLength([[1, 8], ["Hello"], [false, true, false, false]]));

class GenericNumber<T, R> {
  myBad: R;
  zeroValue: T;
  add: (x: T, y: T) => T;
}

const myGenericNumber = new GenericNumber<number, boolean>();
myGenericNumber.zeroValue = 0;
myGenericNumber.myBad = false;
myGenericNumber.add = function(x, y) {
  return x + y;
};

const stringNumeric = new GenericNumber<string, string>();
stringNumeric.zeroValue = "";
stringNumeric.myBad = "Something something";
stringNumeric.add = function(x, y) {
  return x + y;
};