title: vue.js: Filtering not working as I expect
body: <p>I am using this code to filter OUT any parts with categories OTHER than '1', '2', or '3' but the displayed list isn't filtering out cats like 'LG' and 'NHA'. I am using filter incorrectly?</p>
  
  <pre><code>return this.components.filter((c) =&gt; {
      if (c.cat in ['1', '2', '3']) {
          return c;
      }
  });
  </code></pre>