p.
  <span class="location-badge">exported from <a href="/angular2/di">angular2/di</a></span>
  defined in <a href="https://github.com/angular/angular/tree/master/modules/angular2/src/di/key.js#L17">angular2/src/di/key.js (line 17)</a>

:markdown
  A unique object used for retrieving items from the Injector.
  
  [Key]s have:
  - system wide unique [id].
  - [token] usually the [Type] of the instance.
  
  [Key]s are used internaly in [Injector] becouse they have system wide unique [id]s which allow the injector to
  index in arrays rather ther look up items in maps.
  
.l-main-section
  h2 Members
  .l-sub-section
    h3 constructor

    
    pre.prettyprint
      code.
        (token, id)

    

    :markdown
      




  .l-sub-section
    h3 get

    
    pre.prettyprint
      code.
        (token)

    

    :markdown
      Retrieve a [Key] for a token.





  .l-sub-section
    h3 id

    

    :markdown
      





  .l-sub-section
    h3 metadata

    

    :markdown
      





  .l-sub-section
    h3 numberOfKeys

    

    :markdown
      





  .l-sub-section
    h3 token

    

    :markdown