title: How to filter FirebaseListObservable on client side?
body: <p>I am using AngularFire2 within an Angular web app. Due to the query limitations of Firebase, I can't form a query that delivers exactly the data I need (At least not without making major changes to my schema). </p>
  
  <p>So I want to apply an additional client-side filter criteria within javascript (typescript). How do I do this? Can I somehow add a filter function to the observable? Below is a fragment that illustrates what I'm doing.</p>
  
  <p>In the HTML Template for the component, I have something like this below. The "jobs" variable in the html fragment is a FirebaseListObservable. </p>
  
  <pre><code>&lt;tr *ngFor="let job of jobs | async"&gt; 
    .. fill in the table rows
  </code></pre>
  
  <p>The component code looks like this:</p>
  
  <pre><code>   // in the member declaration of the class
     jobs : FirebaseListObservable&lt;Job[]&gt;;
  
     ...
     // Notice in ngOnInit(), I'm filtering the jobs list using the the
     // Firebase criteria. But I want to filter on an additional field. 
     // Firebase allows only single field criteria, so I'm looking for 
     // a way to apply an additional client-side filter to jobs to eliminate
     // some additional records. 
  
     ngOnInit(){
        this.jobs = this.af.database.list("/jobs/", {query: {orderByChild : "companyKey", equalTo:someKey}})
     }
  </code></pre>
  
  <p>Is there a way to apply a filter component on "this.jobs" so that I can apply a local (client-side) filter?</p>