title: Checkbox is always checked whatever I choose
body: <p>Hello I am building a form with 1 checkbox. The rest of the form fields work fine but whether the checkbox is checked or not the value is always 'on'.</p>
  
  <p>My code:</p>
  
  <pre><code>&lt;input  id="checkbox_&lt;?=$row['csid'];?&gt;" type="checkbox" &lt;?php if($row['feedbackVisible'] == 'yes') { echo "checked='true'";}?&gt; &gt;
  </code></pre>
  
  <p>and how i get value with jQuery:</p>
  
  <pre><code>var review_visible_website = $('#checkbox_'+ modalId).val();
  </code></pre>
  
  <p>The checkbox starts checked but if i uncheck it, it still gives me value 'on'. What am I doing wrong?</p>