title: angular sort by on ngfor
body: <p>I have the following ngFor statement and I want to sort by price.
  <a href="https://plnkr.co/edit/DC8I8DRB5UKhvWf6Sppl?p=preview" rel="nofollow noreferrer">https://plnkr.co/edit/DC8I8DRB5UKhvWf6Sppl?p=preview</a></p>
  
  <pre><code>&lt;div *ngFor="let coin of keys(); let i = index;"&gt;{{feeds[coin].price}}&lt;/div&gt;
  
  export class PricingTableComponent{
  
    public feeds:  FeedItemDictionary = {};
  
    constructor(service: PricingApiService,private route:ActivatedRoute) {   
  
        this.feeds["btc"] = {price : 1,coin : "BitCoin"} ;
        this.feeds["eth"] = {price : 2,coin : "Etherium"} ;
        //... 1300 like this...
      });
    }
  
    keys() {
      return Object.keys(this.feeds);
    }
  }
  
  interface FeedItemDictionary {
    [ index: string ]: FeedItem // price and coin memebers
  }
  </code></pre>
  
  <p>the problem is that this is a dictionary (I must use a dictionary or map).<br>
  Is it possible to sort by value member?<br>
  Can you please fix my example in plnkr?<br>
  Thanks  </p>