Toggle class to an element by click another element
<p>I want to click on an element to toggle a class being referenced on a completely unrelated element (not a child, parent or sibling)</p>

<p>For example, initially the code would look like this</p>

<pre><code>&lt;a id="button"&gt;Button&lt;/a&gt;

&lt;div class="navigation"&gt;
Foo
&lt;/div&gt;
</code></pre>

<p>When the user clicks the element with the id <code>button</code> the HTML would change to look like this (the class "open" is referenced on element with "navigation" already referenced":</p>

<pre><code>&lt;a id="button"&gt;Button&lt;/a&gt;

&lt;div class="navigation open"&gt;
Foo
&lt;/div&gt;
</code></pre>

<p>The user should be able to toggle the class by clicking the element with the id <code>button</code>.</p>

<p>I would like to use pure javascript to achieve this effect.</p>