title: How to get all checked checkboxes
body: <p>I have a set of input checkboxes with the same name
  and I would like to determine which checkboxes have been checked using javascript, how can I achieve that?
  I know only how to get all the checkboxes as follows:</p>
  
  <pre><code>var checkboxes = document.getElementsByName('mycheckboxes');
  </code></pre>