title: Get column in a row in a table if that row has a selected checkbox
body: <p>I have a table like the following</p>
  
  <pre><code>&lt;table id="adminTable"&gt;
  &lt;thead&gt;
  &lt;tr&gt;
  &lt;th&gt;&lt;/th&gt;
  &lt;th&gt;Username&lt;/th&gt;
  &lt;th&gt;Email&lt;/th&gt;
  &lt;tr&gt;
  &lt;/thead&gt;
  &lt;tbody&gt;
  &lt;tr&gt;&lt;td&gt;&lt;input type='checkbox' name='selected_users[]' value='User1'/&gt;&lt;/td&gt;&lt;td&gt;User1&lt;/td&gt;&lt;td&gt;mail1@mail.com&lt;/td&gt;&lt;/tr&gt;
  &lt;tr&gt;&lt;td&gt;&lt;input type='checkbox' name='selected_users[]' value='User2'/&gt;&lt;/td&gt;&lt;td&gt;User2&lt;/td&gt;&lt;td&gt;mail2@mail.com&lt;/td&gt;&lt;/tr&gt;
  ...
  &lt;/tbody&gt;
  &lt;/table&gt;
  </code></pre>
  
  <p>I have a button below which calls a javascript-function.
  This function then should get all the emails for the users which were selected via their checkboxes...</p>
  
  <p>I am quite new to Javascript and jQuery an am not sure of how to achieve this...
  But I can use plain Javascript or use jQuery...</p>
  
  <p>What I already found was <a href="http://jsfiddle.net/FnDvL/" rel="nofollow noreferrer">this</a>, but I can't get it to help me, because I don't want a button in my row (multiple selections shall be possible via the checkboxes).</p>