title: get prev and next items in array
body: <p>i have an array of numbers</p>
  
  <pre><code>var projects = [ 645,629,648 ];
  </code></pre>
  
  <p>and a number 645</p>
  
  <p>i need to get the next(629) and prev(648) numbers?</p>
  
  <p>can i do it with jquery?</p>