title: How to compare a property value in multiple objects of an array?
body: <p>How can I compare a property value in multiple objects of an array? 
  I have a few objects in array <code>x</code>.</p>
  
  <pre><code>var arr = [{a:1, b:2, c:3, d:4}, {a:1, x:2, y:3, z:4}, ...]
  </code></pre>
  
  <p>I want to compare and return true if the value of <code>'a'</code> is same in all the objects in the array</p>