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        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - classList.toggle(name, force) treats undefined `force` argument as false"
   href="https://bugs.webkit.org/show_bug.cgi?id=148582">148582</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>classList.toggle(name, force) treats undefined `force` argument as false
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>WebKit Nightly Build
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>HTML DOM
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>m.goleb+bugzilla&#64;gmail.com
          </td>
        </tr></table>
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        <pre>Test case:

var div = document.createElement('div');
div.classList.toggle('a', undefined); // &lt;div&gt;&lt;/div&gt;

`toggle` should add the class and not treat `undefined` as false.

Chrome &amp; Edge also share this bug. Firefox implements it correctly.

Chrome bug report: <a href="https://code.google.com/p/chromium/issues/detail?id=489665">https://code.google.com/p/chromium/issues/detail?id=489665</a></pre>
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