title: Shorter way to check multiple or conditions
body: <p>Is there any easier way of checking one variables value against several others? Currently I'm using code like this:</p>
  
  <pre><code>if(a[i] == a[i-13] || a[i] == a[i+13] || a[i] == a[i-1] || a[i] == a[i+1]){
    //my code
  }
  </code></pre>
  
  <p>Now, is there a shorter way to do this? I know I can use a <a href="https://developer.mozilla.org/en/JavaScript/Reference/Statements/switch" rel="noreferrer">switch</a>, but then I'd have to write my function several times. Is there an easier way of doing this?</p>