title: PHP getting value immediately after clicking on checkbox
body: <p>How to get value from checkbox or radio button immediately after clicking on it and write it in textfield without using reset or submit button?</p>
  
  <pre><code>&lt;input type="checkbox" name="age" value="21-29"&gt;21-29 &lt;input type="text" name="yourAge" value=""&gt;
  </code></pre>