title: select object data in array javascript
body: <p>I want select some data in object as</p>
  
  <pre><code>arr: [{number: '1', class: 'a',code: 'aaa111'},
        {number: '2', class: 'b', code: 'bbb222'},
        {number: '3',class: 'c',code: 'ccc333'}
  ];
  </code></pre>
  
  <p>How to do want just class ???</p>