Array.push() and unique items
<p>I have a simple case of pushing unique values into array. It looks like this:</p>

<pre><code>  this.items = [];

  add(item) {
    if(this.items.indexOf(item) &gt; -1) {
      this.items.push(item);
      console.log(this.items);
    }
  }
</code></pre>

<p>Seems pretty straight-forward, right? No, as it appears. It doesn't add any values. I am sure it's some kind of silly mistake on my side, but I can't seem to find it.</p>