title: Add an onchange event listener to an html input field
body: <p>I would like to add an <code>onchange</code> event to those input fields without jquery:</p>
  
  <pre><code>&lt;input type="text" id="cbid.wizard.1._latitude"&gt;
  &lt;input type="text" id="cbid.wizard.1._longitude"&gt;
  </code></pre>
  
  <p>I can already call the object with</p>
  
  <pre><code>&lt;script type="text/javascript"&gt;
      alert(document.getElementById('cbid.wizard.1._latitude').id);
  &lt;/script&gt;
  </code></pre>
  
  <p>In the end, I want to add this behaviour, that if you enter a pair of coordinates into the first input, I will spread the pair over the two input fields?</p>
  
  <p>How do I add an <code>onchange</code> event with javascript? </p>