title: TypeScript initiate an empty interface object
body: <p>Im building an app using angular 5 ( TS ),
  i got stuck trying to initiate an empty object of my interface.
  <br>
  So the only acceptable solution i have seen is this one:</p>
  
  <pre><code>article: Article = {} as Article;
  </code></pre>
  
  <p>Although its seems legit it doesn't work;
  trying to use article["something"] will fail because its just an empty object without any <b> keys </b>.
  <br>
  <br>
  The result im seeking looks something like this: </p>
  
  <pre><code>export interface Article {
  slug: string;
  title: string;
  description: string;
  body: string;
  tagList: string[];
  </code></pre>
  
  <p>after init:</p>
  
  <pre><code>article = { 'slug': '', 'title': '', 'description': '', body: '', tagList: '[]' }
  </code></pre>