title: How to shorten my conditional statements
body: <p>I have a very long conditional statement like the following:</p>
  
  <pre><code>if(test.type == 'itema' || test.type == 'itemb' || test.type == 'itemc' || test.type == 'itemd'){
      // do something.
  }
  </code></pre>
  
  <p>I was wondering if I could refactor this expression/statement into a more concise form.</p>
  
  <p>Any idea on how to achieve this?</p>