Why you should love TypeScript - A practical guide

Learn about the new and awesome features of Typescript. See how Typescript can help with both React and Angular. Make your React coding experience even better with static Types. See what are the practical benefits while not being a 'type' nazi.

Transcript

1. @deepu105 #Devoxx2018 By Deepu K Sasidharan, XebiaLabs November 13, 2018 TypeScript: Why you should love it!
2. @deepu105 #Devoxx2018 About Me Deepu K Sasidharan Javascript advocate & OSS aficionado Co-lead Senior product developer Robotics & Astronomy enthusiast https://www.packtpub.com/application-development/full-stack-development-jhipster
3. @deepu105 #Devoxx2018 About XebiaLabs
4. @deepu105 #Devoxx2018 What about you? How many of you are Java developers? How many are web developers? Who likes JavaScript? Who likes TypeScript better? Are you a fan of: Angular React Vue.js
5. @deepu105 #Devoxx2018 What about you? Who attended my TypeScript deep-dive session yesterday?
6. Why many Java developers hate frontend development?
7. @deepu105 #Devoxx2018 Frontend options 8 years ago =
8. @deepu105 #Devoxx2018 The rise of MV* frameworks
9. @deepu105 #Devoxx2018
10. @deepu105 #Devoxx2018 “Yet Another Framework Syndrome”
11. How to make Java developers like(love) JavaScript
13. @deepu105 #Devoxx2018 What is TypeScript A strict syntactical superset of JavaScript - upto ES2019(ES10) JavaScript that scales Optional static typing support Transpiles to JavaScript Maintained by Microsoft with major collaboration from Google Great editor and IDE support
14. I hate transpiling my code, but if have to do so I’ll do it with TypeScript
15. @deepu105 #Devoxx2018 Why TypeScript Type safety and Type inference Great IDE support Easier refactoring Better linting and error identification Features from the Future Much better code style in React and Angular
16. Getting started!
17. @deepu105 #Devoxx2018 Install TypeScript npm install -g typescript tsc -init tsc -w
18. @deepu105 #Devoxx2018 Working with JS allowJs: Allow javascript files to be compiled checkJs: Report errors in .js files. // @ts-nocheck // @ts-check Supports JSDoc syntax for type specification
19. Language features
20. @deepu105 #Devoxx2018 Basic types Boolean -> const foo: boolean = true; Number -> const foo: number = 10; String -> const foo: string = ‘hello’; Array -> const foo: string[] = [‘foo’, ‘bar’]; const foo: Array<string> = [‘foo’, ‘bar’];
21. @deepu105 #Devoxx2018 Special types Any -> const foo: any = { foo: 'bar' }; Object -> const foo: object = { foo: 'bar' }; Tuple -> const foo: [string, boolean] = ['foo', 10]; Void -> const foo: void = undefined; Undefined -> const foo: undefined = undefined; Null -> const foo: null = undefined; Never -> function error(message: string): never { throw new Error(message); }
22. @deepu105 #Devoxx2018 Enum types enum Color {Red, Green, Blue} let c: Color = Color.Green; enum Color {Red = 1, Green = 2, Blue = 4} let c: Color = Color.Green; enum Color {Red = "RED", Green = "GREEN", Blue = "BLUE"} let c: Color = Color.Green;
23. @deepu105 #Devoxx2018 Interfaces interface Person { name: string; age: number; address?: string; sayHi: Function; } let deepu: Person = { name: 'deepu', age: 32, sayHi: () => 'Hello there!' }
24. @deepu105 #Devoxx2018 Function interfaces interface AddFunction { (a: number, b: number): number } const add: AddFunction = (a, b) => { return a + b; }
25. @deepu105 #Devoxx2018 Extending & implementing interfaces/classes interface DevoxxAttendee extends Person { isHip: boolean; } interface DevoxxAttendee extends You { isHip: boolean; }
26. @deepu105 #Devoxx2018 Class modifiers class Greeter { private greeting: string; protected name: string = `greeter`; readonly foo: string = `bar`; constructor(message: string){ this.greeting = message } public greet(){ return `Hello ${this.greeting} from ${this.name}`; } }
27. @deepu105 #Devoxx2018 Static properties class Greeter { static greeter: string = `foo`; private greeting: string; constructor(message: string){ this.greeting = message } public greet(){ return `Hello ${this.greeting} from ${Greeter.greeter}`; } }
28. @deepu105 #Devoxx2018 Abstract classes abstract class Greeter { static greeter: string = `foo`; private greeting: string; constructor(message: string){ this.greeting = message } public greet(){ return `Hello ${this.greeting} from ${Greeter.greeter}`; } }
29. @deepu105 #Devoxx2018 Function overloading function add(x: string, y: string): string; function add(x: number, y: number): number; function add(x: any, y: any): any { if (typeof x == 'string' && typeof y == 'string') { return `${x}:${y}`; } else { return x + y; } } add(10, 10); add('10', '10');
30. @deepu105 #Devoxx2018 Generics class Greeter<T> { private greeting: T; constructor(message: T){ this.greeting = message } public greet(){ return `Hello ${this.greeting}`; } } const greeter = new Greeter<string>('world'); const greeter2 = new Greeter<number>(10);
31. @deepu105 #Devoxx2018 Decorators Methods Classes Properties Parameters Accessor
32. @deepu105 #Devoxx2018 Decorators @sealed class Greeter { greeting: string; constructor(message: string) { this.greeting = message; } @log greet() { return "Hello, " + this.greeting; } }
33. @deepu105 #Devoxx2018 Mixins class Runner { speed = 0; run(distance: number) { return distance / this.speed; } } class Person implements Runner { speed = 0; setSpeed(speed: number) { this.speed = speed; } run(distance: number): number { return 0; } } applyMixins(Person, [Runner]);
34. Very good type inference
35. Advanced types
36. @deepu105 #Devoxx2018 Literal types type Color = "red" | "blue" | "green"; type Binary = 1 | 0;
37. @deepu105 #Devoxx2018 Intersection & Union types interface Runner { speed: number; run(distance: number): number; } interface Swimmer { speed: number; swim(distance: number): number; } type Person = Runner & Swimmer type Person = Runner | Swimmer
38. @deepu105 #Devoxx2018 Type guards function isSwimmer(person: Runner | Swimmer): person is Swimmer { return (<Swimmer>person).swim !== undefined; } function isRunner(person: Runner | Swimmer): person is Runner { return (<Runner>person).run !== undefined; } if (isSwimmer(person)) { person.swim(10) } if (isRunner(person)) { person.run(10) }
39. @deepu105 #Devoxx2018 Mapped types type Readonly<T> = { readonly [P in keyof T]: T[P]; } type Partial<T> = { [P in keyof T]?: T[P]; } type PersonPartial = Partial<Person>; type ReadonlyPerson = Readonly<Person>;
40. @deepu105 #Devoxx2018 Type alias type GreeterAlias = Greeter type StringTuple2 = [string, string]
41. @deepu105 #Devoxx2018 Index types function pluck<T, K extends keyof T>(o: T, names: K[]): T[K][] { return names.map(n => o[n]); } interface Person { name: string; age: number; } let person: Person = { name: 'Jarid', age: 35 }; let strings: string[] = pluck(person, ['name']);
42. Kickstarting Angular, Vue or React
43. @deepu105 #Devoxx2018
44. @deepu105 #Devoxx2018
45. @deepu105 #Devoxx2018
46. An optimal React, Angular or VueJS stack with TypeScript for Java developers
47. @deepu105 #Devoxx2018 Want to learn more about JHipster? Come to our BOF tonight!
48. @deepu105 #Devoxx2018 VsCode • Best TypeScript support among available options • Written in TypeScript and hence supports it natively • Plugin for Tslint • Lot of TypeScript utility plugins, like TypeScript Hero
49. https://jhipster.tech @java_hipster Full Stack Development with JHipster • Amazon: https://goo.gl/k1NBAv • Packt: https://goo.gl/XvQLeN
50. Thank you! Please rate the talk if you liked it!