readme.md

Typescript Cheatsheet

A minimalist typescript cheatsheet to get started quickly

// Install typescript
npm install -g concurrently lite-server typescript

// Run the .ts
tsc typescript-cheatsheet --watch

// In another terminal window
node typescript-cheatsheet

typescript-cheatsheet.ts

export {};
let message = "Hello";
console.log(message);

let isBeginner: boolean = true;
let total: number = 0;
let name: string = "Joe";

let sentence: string = `My name is ${name}`;

console.log(sentence);

let list01: number[] = [1, 2, 3];
let list02: Array<number> = [1, 2, 3];

let person01: [string, number] = ["Bob", 30];

enum Color {
  Reg,
  Green,
  Blue
}

let c: Color = Color.Green;
console.log(c);

let myVariable: any = 10;

function hasName(obj: any): obj is { name: string } {
  return !!obj && typeof obj === "object" && "name" in obj;
}

if (hasName(myVariable)) {
  console.log(myVariable.name);
}

let multiType: number | boolean;
multiType = 10;
multiType = true;

function add(num1: number, num2?: number): number {
  return num1 + num2;
}

add(5);

function fullName(person: { firstName: string; lastName: string }): void {
  console.log(person.firstName, person.lastName);
}

let p = {
  firstName: "Bob",
  lastName: "Dylan"
};

fullName(p);

interface Person {
  firstName: string;
  lastName: string;
  address?: string;
}

function user(person: Person): void {
  console.log(person.firstName, person.lastName);
}

user({ firstName: "Johnny", lastName: "Cash" });

class Employee {
  employeeName: string;
  //   public employeeName: string; // full access
  //   private employeeName: string; // no access
  //   protected employeeName: string; // acess within a derived class

  constructor(name: string) {
    this.employeeName = name;
  }

  greet() {
    console.log("Good morning", this.employeeName);
  }
}

let emp1 = new Employee("Kenny");
console.log(emp1.employeeName);
emp1.greet();

class Manager extends Employee {
  constructor(managerName: string) {
    super(managerName);
  }

  delegateWork() {
    console.log("Manager delegating tasks");
  }
}

let m1 = new Manager("Bruce");
m1.delegateWork();
m1.greet();
console.log(m1.employeeName);