title: Grey-out (disable) HTML textarea when checkbox is ticked
body: <p>I don't really know much Javascript yet, I was hoping somebody could help me understand how to solve my problem:</p>
  
  <p>My HTML form has a <code>checkbox</code> and then a <code>textarea</code>:</p>
  
  <pre><code>&lt;form&gt;
  &lt;input type="checkbox" name="detailsgiven" /&gt;
  &lt;textarea name="details"&gt;&lt;/textarea&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>I want it so that the <code>textarea</code> gets disabled when the <code>checkbox</code> is ticked so that the user cannot click it and enter text.</p>
  
  <p>I've had a look here and on google, I couldn't find any clear examples of how to do it.</p>
  
  <p>I'm guessing this can be done in Javascript, but I'm feeling a bit out of my depth. Can somebody explain to me how to do this, preferably without using a third party library?</p>