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TypeScript: coding JavaScript without the pain
- 1. TypeScript coding JavaScript without the pain @Sander_Mak Luminis Technologies
- 2. INTRO @Sander_Mak: SeniorSoftware Engineer at Author: Dutch Java Magazine blog @ branchandbound.net Speaker:
- 3. AGENDA Why TypeScript? Language introduction / live-coding TypeScript and Angular Comparison with TS alternatives Conclusion
- 4. WHAT'S WRONG WITHJAVASCRIPT? Dynamic typing Lack of modularity Verbose patterns (IIFE)
- 5. WHAT'S WRONG WITHJAVASCRIPT? Dynamic typing Lack of modularity Verbose patterns (IIFE) In short: JavaScript development scales badly
- 6. WHAT'S GOOD ABOUTJAVASCRIPT? It's everywhere Huge amount of libraries Flexible
- 7. WISHLIST Scalable HTML5clientside development Modular development Easily learnable for Java developers Non-invasive (existing libs, browser support) Long-term vision Clean JS output (exit strategy)
- 8. WISHLIST Scalable HTML5clientside development Modular development Easily learnable for Java developers Non-invasive (existing libs, browser support) Long-term vision Clean JS output (exit strategy) ✓✓✓✓✓✓
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- 12. TYPESCRIPT Superset ofJavaScript Optionally typed Compiles to ES3/ES5 No special runtime 1.0 in April 2014, future ES6 alignment
- 13. TYPESCRIPT Superset ofJavaScript Optionally typed Compiles to ES3/ES5 No special runtime 1.0 in April 2014, future ES6 alignment In short: Lightweight productivity booster
- 14. GETTING STARTED $npm install -g typescript $ mv mycode.js mycode.ts $ tsc mycode.ts
- 15. GETTING STARTED $npm install -g typescript $ mv mycode.js mycode.ts $ tsc mycode.ts May even find problems in existing JS!
- 16. OPTIONAL TYPES Typeannotations > var a = 123 > a.trim() ! TypeError: undefined is not a function JS > var a: string = 123 > a.trim() ! Cannot convert 'number' to 'string'. TS runtime compile-time
- 17. OPTIONAL TYPES Typeannotations > var a = 123 > a.trim() ! TypeError: undefined is not a function JS > var a: string = 123 > a.trim() ! Cannot convert 'number' to 'string'. TS Type inference > var a = 123 > a.trim() ! The property 'trim' does not exist on value of type 'number'. Types dissapear at runtime
- 18. OPTIONAL TYPES Objectvoid boolean integer long short ... String char Type[] any void boolean number string type[]
- 19. OPTIONAL TYPES Typesare structural rather than nominal TypeScript has function types: var find: (elem: string, elems: string[]) => string = function(elem, elems) { .. }
- 20. OPTIONAL TYPES Typesare structural rather than nominal TypeScript has function types: var find: (elem: string, elems: string[]) => string = function(elem, elems) { .. }
- 21. DEMO: OPTIONAL TYPES code Code: http://bit.ly/tscode
- 22. INTERFACES interface MyInterface{ // Call signature (param: number): string member: number optionalMember?: number myMethod(param: string): void } ! var instance: MyInterface = ... instance(1)
- 23. INTERFACES Use themto describe data returned in REST calls $.getJSON('user/123').then((user: User) => { showProfile(user.details) }
- 24. INTERFACES TS interfacesare open-ended: interface JQuery { appendTo(..): .. .. } interface JQuery { draggable(..): .. .. jquery.d.ts } jquery.ui.d.ts
- 25. OPTIONAL TYPES: ENUMS enum Language { TypeScript, Java, JavaScript } ! var lang = Language.TypeScript var ts = Language[0] ts === "TypeScript" enum Language { TypeScript = 1, Java, JavaScript } ! var ts = Language[1]
- 26. GOING ALL THEWAY Force explicit typing with noImplicitAny var ambiguousType; ! ambiguousType = 1 ambiguousType = "text" noimplicitany.ts $ tsc --noImplicitAny noimplicitany.ts
- 27. GOING ALL THEWAY Force explicit typing with noImplicitAny var ambiguousType; ! ambiguousType = 1 ambiguousType = "text" noimplicitany.ts $ tsc --noImplicitAny noimplicitany.ts error TS7005: Variable 'ambiguousType' implicitly has an 'any' type.
- 28. TYPESCRIPT CLASSES Canimplement interfaces Inheritance Instance methods/members Static methods/members Single constructor Default/optional parameters ES6 class syntax similar different
- 29. DEMO: TYPESCRIPT CLASSES code Code: http://bit.ly/tscode
- 30. ARROW FUNCTIONS Implicitreturn No braces for single expression Part of ES6
- 31. ARROW FUNCTIONS Implicitreturn No braces for single expression Part of ES6 function(arg1) { return arg1.toLowerCase(); }
- 32. ARROW FUNCTIONS Implicitreturn No braces for single expression Part of ES6 function(arg1) { return arg1.toLowerCase(); } (arg1) => arg1.toLowerCase();
- 33. ARROW FUNCTIONS Implicitreturn No braces for single expression Part of ES6 function(arg1) { return arg1.toLowerCase(); } (arg1) => arg1.toLowerCase(); Lexically-scoped this (no more 'var that = this')
- 34. DEMO: ARROW FUNCTIONS code Code: http://bit.ly/tscode
- 35. TYPE DEFINITIONS Howto integrate existing JS code? Ambient declarations Any-type :( Type definitions lib.d.ts Separate compilation: tsc --declaration file.ts
- 36. TYPE DEFINITIONS DefinitelyTyped.org Community provided .d.ts files for popular JS libs How to integrate existing JS code? Ambient declarations Any-type :( Type definitions lib.d.ts Separate compilation: tsc --declaration file.ts
- 37. INTERNAL MODULES moduleStorageModule { export interface Storage { store(content: string): void } ! var privateKey = 'storageKey'; export class LocalStorage implements Storage { store(content: string): void { localStorage.setItem(privateKey, content); } } ! export class DevNullStorage implements Storage { store(content: string): void { } } } ! var storage: StorageModule.Storage = new StorageModule.LocalStorage(); storage.store('testing');
- 38. INTERNAL MODULES moduleStorageModule { export interface Storage { store(content: string): void } ! var privateKey = 'storageKey'; export class LocalStorage implements Storage { store(content: string): void { localStorage.setItem(privateKey, content); } } ! export class DevNullStorage implements Storage { store(content: string): void { } } } ! var storage: StorageModule.Storage = new StorageModule.LocalStorage(); storage.store('testing');
- 39. INTERNAL MODULES moduleStorageModule { export interface Storage { store(content: string): void } ! var privateKey = 'storageKey'; export class LocalStorage implements Storage { store(content: string): void { localStorage.setItem(privateKey, content); } } ! export class DevNullStorage implements Storage { store(content: string): void { } } } ! var storage: StorageModule.Storage = new StorageModule.LocalStorage(); storage.store('testing');
- 40. INTERNAL MODULES moduleStorageModule { export interface Storage { store(content: string): void } ! var privateKey = 'storageKey'; export class LocalStorage implements Storage { store(content: string): void { localStorage.setItem(privateKey, content); } } ! export class DevNullStorage implements Storage { store(content: string): void { } } } ! var storage: StorageModule.Storage = new StorageModule.LocalStorage(); storage.store('testing');
- 41. INTERNAL MODULES TSinternal modules are open-ended: ! module Webshop { export class Cart { .. } } /// <reference path="cart.ts" /> module Webshop { export class Catalog { .. } cart.ts } main.ts
- 42. INTERNAL MODULES TSinternal modules are open-ended: ! module Webshop { export class Cart { .. } } /// <reference path="cart.ts" /> module Webshop { export class Catalog { .. } cart.ts } main.ts Can be hierarchical: module Webshop.Cart.Backend { ... }
- 43. INTERNAL MODULES TSinternal modules are open-ended: ! module Webshop { export class Cart { .. } } /// <reference path="cart.ts" /> module Webshop { export class Catalog { .. } cart.ts } main.ts Can be hierarchical: module Webshop.Cart.Backend { ... } Combine modules: $ tsc --out main.js main.ts
- 44. DEMO: PUTTING ITALL TOGETHER code Code: http://bit.ly/tscode
- 45. EXTERNAL MODULES CommonJS Asynchronous Module Definitions $ tsc --module common main.ts $ tsc --module amd main.ts Combine with module loader
- 46. EXTERNAL MODULES 'Standards-based',use existing external modules Automatic dependency management Lazy loading AMD verbose without TypeScript Currently not ES6-compatible
- 47. DEMO + + =
- 48. DEMO: TYPESCRIPT ANDANGULAR code Code: http://bit.ly/tscode
- 49. BUILDING TYPESCRIPT $tsc -watch main.ts grunt-typescript grunt-ts gulp-type (incremental) gulp-tsc
- 50. TOOLING IntelliJ IDEA WebStorm plugin
- 51. TYPESCRIPT vs ES6HARMONY Complete language + runtime overhaul More features: generators, comprehensions, object literals Will take years before widely deployed No typing (possible ES7)
- 52. TYPESCRIPT vs COFFEESCRIPT Also a compile-to-JS language More syntactic sugar, still dynamically typed JS is not valid CoffeeScript No spec, definitely no Anders Hejlsberg... Future: CS doesn't track ECMAScript 6 !
- 53. TYPESCRIPT vs DART Dart VM + stdlib (also compile-to-JS) Optionally typed Completely different syntax & semantics than JS JS interop through dart:js library ECMA Dart spec
- 54. TYPESCRIPT vs CLOSURECOMPILER Google Closure Compiler Pure JS Types in JsDoc comments Less expressive Focus on optimization, dead-code removal
- 55. WHO USES TYPESCRIPT? (duh)
- 56. CONCLUSION Internal modules Classes/Interfaces Some typing External modules Type defs More typing Generics Type defs -noImplicitAny
- 57. CONCLUSION TypeScript allowsfor gradual adoption Internal modules Classes/Interfaces Some typing External modules Type defs More typing Generics Type defs -noImplicitAny
- 58. CONCLUSION Some downsides: Still need to know some JS quirks Current compiler slowish (faster one in the works) External module syntax not ES6-compatible (yet) Non-MS tooling lagging a bit
- 59. CONCLUSION High value,low cost improvement over JavaScript Safer and more modular Solid path to ES6
- 60. MORE TALKS TypeScript: Wednesday, 11:30 AM, same room !Akka & Event-sourcing Wednesday, 8:30 AM, same room @Sander_Mak Luminis Technologies
- 61. RESOURCES Code: http://bit.ly/tscode ! Learn: www.typescriptlang.org/Handbook @Sander_Mak Luminis Technologies