Angular 2：なぜTypeScriptなのか？

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function processPurchase(purchaser, details){ } 

class User { } 

class ExternalSystem { }
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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

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

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

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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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 };
      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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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");

      
      

        
        
        
      

    
        
        
        
      
      

        
        
        
      

    
    

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