TypeScript 
coding JavaScript 
without the pain 
@Sander_Mak Luminis Technologies
INTRO 
@Sander_Mak: Senior Software Engineer at 
Author: 
Dutch 
Java 
Magazine 
blog @ branchandbound.net 
Speaker:
AGENDA 
Why TypeScript? 
Language introduction / live-coding 
TypeScript and Angular 
Comparison with TS alternatives 
Conclusion
WHAT'S WRONG WITH JAVASCRIPT? 
Dynamic typing 
Lack of modularity 
Verbose patterns (IIFE)
WHAT'S WRONG WITH JAVASCRIPT? 
Dynamic typing 
Lack of modularity 
Verbose patterns (IIFE) 
In short: JavaScript development scales badly
WHAT'S GOOD ABOUT JAVASCRIPT? 
It's everywhere 
Huge amount of libraries 
Flexible
WISHLIST 
Scalable HTML5 clientside development 
Modular development 
Easily learnable for Java developers 
Non-invasive (existing libs, browser support) 
Long-term vision 
Clean JS output (exit strategy)
WISHLIST 
Scalable HTML5 clientside development 
Modular development 
Easily learnable for Java developers 
Non-invasive (existing libs, browser support) 
Long-term vision 
Clean JS output (exit strategy) 
✓✓✓✓✓✓
2.0 licensed
2.0 licensed
TYPESCRIPT 
Superset of JavaScript 
Optionally typed 
Compiles to ES3/ES5 
No special runtime 
1.0 in April 2014, future ES6 alignment
TYPESCRIPT 
Superset of JavaScript 
Optionally typed 
Compiles to ES3/ES5 
No special runtime 
1.0 in April 2014, future ES6 alignment 
In short: Lightweight productivity booster
GETTING STARTED 
$ npm install -g typescript 
$ mv mycode.js mycode.ts 
$ tsc mycode.ts
GETTING STARTED 
$ npm install -g typescript 
$ mv mycode.js mycode.ts 
$ tsc mycode.ts 
May even find problems in existing JS!
OPTIONAL TYPES 
Type annotations 
> 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
OPTIONAL TYPES 
Type annotations 
> 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
OPTIONAL TYPES 
Object void boolean integer 
long 
short 
... 
String 
char 
Type[] 
any void boolean number string type[]
OPTIONAL TYPES 
Types are structural rather than nominal 
TypeScript has function types: 
var find: (elem: string, elems: string[]) => string = 
function(elem, elems) { 
.. 
}
OPTIONAL TYPES 
Types are structural rather than nominal 
TypeScript has function types: 
var find: (elem: string, elems: string[]) => string = 
function(elem, elems) { 
.. 
}
DEMO: OPTIONAL TYPES 
code 
Code: http://bit.ly/tscode
INTERFACES 
interface MyInterface { 
// Call signature 
(param: number): string 
member: number 
optionalMember?: number 
myMethod(param: string): void 
} 
! 
var instance: MyInterface = ... 
instance(1)
INTERFACES 
Use them to describe data returned in REST calls 
$.getJSON('user/123').then((user: User) => { 
showProfile(user.details) 
}
INTERFACES 
TS interfaces are open-ended: 
interface JQuery { 
appendTo(..): .. 
.. 
} 
interface JQuery { 
draggable(..): .. 
.. 
jquery.d.ts } jquery.ui.d.ts
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]
GOING ALL THE WAY 
Force explicit typing with noImplicitAny 
var ambiguousType; 
! 
ambiguousType = 1 
ambiguousType = "text" noimplicitany.ts 
$ tsc --noImplicitAny noimplicitany.ts
GOING ALL THE WAY 
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.
TYPESCRIPT CLASSES 
Can implement interfaces 
Inheritance 
Instance methods/members 
Static methods/members 
Single constructor 
Default/optional parameters 
ES6 class syntax 
similar 
different
DEMO: TYPESCRIPT CLASSES 
code 
Code: http://bit.ly/tscode
ARROW FUNCTIONS 
Implicit return 
No braces for single expression 
Part of ES6
ARROW FUNCTIONS 
Implicit return 
No braces for single expression 
Part of ES6 
function(arg1) { 
return arg1.toLowerCase(); 
}
ARROW FUNCTIONS 
Implicit return 
No braces for single expression 
Part of ES6 
function(arg1) { 
return arg1.toLowerCase(); 
} 
(arg1) => arg1.toLowerCase();
ARROW FUNCTIONS 
Implicit return 
No braces for single expression 
Part of ES6 
function(arg1) { 
return arg1.toLowerCase(); 
} 
(arg1) => arg1.toLowerCase(); 
Lexically-scoped this (no more 'var that = this')
DEMO: ARROW FUNCTIONS 
code 
Code: http://bit.ly/tscode
TYPE DEFINITIONS 
How to integrate 
existing JS code? 
Ambient declarations 
Any-type :( 
Type definitions 
lib.d.ts 
Separate compilation: 
tsc --declaration file.ts
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
INTERNAL MODULES 
module StorageModule { 
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');
INTERNAL MODULES 
module StorageModule { 
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');
INTERNAL MODULES 
module StorageModule { 
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');
INTERNAL MODULES 
module StorageModule { 
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');
INTERNAL MODULES 
TS internal modules are open-ended: 
! 
module Webshop { 
export class Cart { .. } 
} 
/// <reference path="cart.ts" /> 
module Webshop { 
export class Catalog { .. } 
cart.ts } main.ts
INTERNAL MODULES 
TS internal 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 { 
... 
}
INTERNAL MODULES 
TS internal 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
DEMO: PUTTING IT ALL TOGETHER 
code 
Code: http://bit.ly/tscode
EXTERNAL MODULES 
CommonJS 
Asynchronous 
Module 
Definitions 
$ tsc --module common main.ts 
$ tsc --module amd main.ts 
Combine with module loader
EXTERNAL MODULES 
'Standards-based', use existing external modules 
Automatic dependency management 
Lazy loading 
AMD verbose without TypeScript 
Currently not ES6-compatible
DEMO 
+ + 
=
DEMO: TYPESCRIPT AND ANGULAR 
code 
Code: http://bit.ly/tscode
BUILDING TYPESCRIPT 
$ tsc -watch main.ts 
grunt-typescript 
grunt-ts 
gulp-type (incremental) 
gulp-tsc
TOOLING 
IntelliJ IDEA 
WebStorm 
plugin
TYPESCRIPT vs ES6 HARMONY 
Complete language + runtime overhaul 
More features: generators, comprehensions, 
object literals 
Will take years before widely deployed 
No typing (possible ES7)
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 
!
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
TYPESCRIPT vs CLOSURE COMPILER 
Google Closure Compiler 
Pure JS 
Types in JsDoc comments 
Less expressive 
Focus on optimization, dead-code removal
WHO USES TYPESCRIPT? 
(duh)
CONCLUSION 
Internal modules 
Classes/Interfaces 
Some typing 
External modules 
Type defs 
More typing 
Generics 
Type defs 
-noImplicitAny
CONCLUSION 
TypeScript allows for gradual adoption 
Internal modules 
Classes/Interfaces 
Some typing 
External modules 
Type defs 
More typing 
Generics 
Type defs 
-noImplicitAny
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
CONCLUSION 
High value, low cost improvement over JavaScript 
Safer and more modular 
Solid path to ES6
MORE TALKS 
TypeScript: 
Wednesday, 11:30 AM, same room 
!Akka & Event-sourcing 
Wednesday, 8:30 AM, same room 
@Sander_Mak 
Luminis Technologies
RESOURCES 
Code: http://bit.ly/tscode 
! 
Learn: www.typescriptlang.org/Handbook 
@Sander_Mak 
Luminis Technologies

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) ✓✓✓✓✓✓
  • 10.
  • 11.
  • 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.
  • 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.
  • 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