title: Angular 4 with Firebase. How to make random ID?
body: <p>It`s like I make title 'some stuff' and It should make it some-stuff-H5KNWGFGHNWG2(random firebaseId). </p>
  
  <p>What I need to add to my doc chain to make it work?</p>
  
  <p>Is there some random id method like fb.randomId()?</p>
  
  <pre><code>    this.db.collection('posts')
          .doc(this.title.split(' ').join('-') + '-')
            .set({'title': this.title, 'content': this.content});
  </code></pre>
  
  <p>UPD: To better understanding of what I what.</p>
  
  <pre><code>.doc(this.title.split(' ').join('-') + '-'+Some random Id)
  </code></pre>