title: Static Methods and Angular 2 Services in JavaScript ES6
body: <p>While coding an app with Angular 2 and multiple calculation services I faced the following questions: </p>
  
  <ol>
  <li>When do I use static in a Angular service provided on application level? Is that nonsense? </li>
  <li>How does a static method reflect on performance? Lets say a couple hundret objects call at the same time the same static method. Is this method instantiated more than once? </li>
  </ol>
  
  <p>This is a snap of the class, that provides me multiple calculation methods and is instantiated on application level: </p>
  
  <pre><code>@Injectable()
  export class FairnessService {
    constructor(){}
    private static calculateProcentValue(value: number, from: number): number {
      return (Math.abs(value) / Math.abs(from)) * 100;
    }
    public static calculateAllocationWorth(allocation: Allocation): number {
      ...
    }
  }
  </code></pre>
  
  <p>Thanks for helping.</p>