title: Change input form when checkbox is pressed
body: <p>I would like to create a webform which gives users the opportunity to create tickets more easily.</p>
  
  <p>In this webform I have two input forms and a checkbox:
  <img src="https://i.stack.imgur.com/At5xG.png" alt="Screenshot"></p>
  
  <p>What I would like to have is the following (created via PowerPoint):
  <img src="https://i.stack.imgur.com/riXH4.png" alt="Screenshot"></p>
  
  <p>So if the users click the checkbox the webform should automatically disable the second input form and copy the value and/or the placeholder of the first input form. So briefly speaking: If the users click the checkbox the second input form should be exactly like the first one, except that it is disabled.</p>
  
  <p>Unfortunately I have no clue how to do this. By now my code looks like this:</p>
  
  <p>Input field 1 (key user) + checkbox:</p>
  
  <pre><code>&lt;div class="form-group"&gt;
  &lt;label class="control-label col-sm-2" for="keyuser"&gt;Key-User:&lt;/label&gt;
  &lt;div class="col-sm-10"&gt; 
    &lt;input type="keyuser" class="form-control" id="keyuser" placeholder="Username Key-User"&gt;
  
    &lt;div class="checkbox"&gt;
      &lt;label onclick="checkbox()"&gt;
          &lt;input type="checkbox"&gt;
      &lt;/label&gt;Is the affected user
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p></p>
  
  <p>Input field 2 (affected user):</p>
  
  <pre><code>  &lt;div class="form-group"&gt;
  &lt;label class="control-label col-sm-2" for="affuser"&gt;Affected User:&lt;/label&gt;
  &lt;div class="col-sm-10"&gt; 
    &lt;input type="affuser" class="form-control" id="affuser" placeholder="Username affected user"&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p></p>
  
  <p>Checkbox() [it does not work at all right now]:</p>
  
  <pre><code>function checkbox() {
  "use strict";
  if (check === "False") {
      check = "True";
      $('#affuser').attr('placeholder', 'Username Key-User');
  
  } else {
      check = "False";
      $('#affuser').attr('placeholder', 'Username affected user');
  }
  </code></pre>
  
  <p>}</p>
  
  <p>How can I implement the functions mentioned above?</p>