Angular 2：なぜTypeScriptなのか？

, !

- 13 2015 Angular 2 . , , .

Angular 2 TypeScript. , . , TypeScript; .

TypeScript , – , .

, Angular 2 TypeScript, Angular 2 . ES5, ES6 Dart.

TypeScript –

TypeScript – . , . . , , .

TypeScript – , JavaScript. , . . , – TypeScript. , . , TypeScript – .

(intellisense) (, ) , , . , , , , .

, TypeScript , , , ES5. , JavaScript (., JSHint), .

TypeScript – JavaScript

TypeScript – JavaScript, . , .
, .js .ts, . – . , , .

, , Angular 2 TypeScript, , .

TypeScript

– . , .

, . : , – , API.



, – «». , «» , . purchaser.js. , - , .

function processPurchase(purchaser, details){ } 

class User { } 

class ExternalSystem { }

, , . , . – , .

, Purchaser.

interface Purchaser {id: int; bankAccount: Account;} 
class User implements Purchaser {} 
class ExternalSystem implements Purchaser {}

, Purchaser, User ExternalSystem . , TypeScript //.

, TypeScript . «» JavaScript, .

. JavaScript , JavaScript . , , , .

Angular 2 TypeScript . , API, , .

TypeScript

, , . . jQuery.ajax(). ?

, – . . , , – . , , . , ( , ), , .

, , . – ; , , . , , . , , – , .

, jQuery.ajax(url, settings) , , , , , .

.

ajax(url: string, settings?: JQueryAjaxSettings): JQueryXHR; 

interface JQueryAjaxSettings { 
  async?: boolean; 
  cache?: boolean; 
  contentType?: any; 
  headers?: { [key: string]: any; }; 
  //... 
} 

interface JQueryXHR { 
  responseJSON?: any; //... 
}

:

• – .
• settings . , – , .
• JQueryXHR, .

, :string, :JQueryAjaxSettings JQueryXHR – . «», . , . , – , . , - , – , , .

TypeScript , JavaScript – , , jQuery.ajax(url, settings) – TypeScript. , TypeScript , . , , – . , .

TypeScript ?

– , . , TypeScript , , . . , ImmutableJS, Person.

const PersonRecord = Record({name:null, age:null}); 

function createPerson(name, age) { 
  return new PersonRecord({name, age}); 
} 

const p = createPerson("Jim", 44); 

expect(p.name).toEqual("Jim");

? Person:

interface Person { name: string, age: number };

:

function createPerson(name: string, age: number): Person { 
  return new PersonRecord({name, age}); 
}

TypeScript . , PersonRecord Person, PersonRecord . , , : “, TypeScript !” . TypeScript . : , 100% , . , .

, :

function createPerson(name: string, age: number): Person { 
  return <any>new PersonRecord({name, age}); 
}

:

interface Person { name: string, age: number }; 

const PersonRecord = Record({name:null, age:null}); 

function createPerson(name: string, age: number): Person { 
  return <any>new PersonRecord({name, age}); 
} 

const p = createPerson("Jim", 44); 

expect(p.name).toEqual("Jim");

, .  —   —  .

, TypeScript « » . . , - – , . , . , .

. 95% , 100% — , , .

JavaScript . , , «», . TypeScript JavaScript, . .

TypeScript?

: ES5, ES6 (Babel), TypeScript, Dart, PureScript, Elm, .. TypeScript?

ES5. ES5 TypeScript: . . file watcher’, , . .

ES6 , TypeScript. , , ES6, . TypeScript .

Elm PureScript – , , TypeScript. Elm PureScript , ES5.

, , TypeScript – , . TypeScript 95% , JavaScript. , ES6: , , (, «» Chrome). , JavaScript.