title: Defining the number of options to be selected from dropdown selection html
body: <p>Is there a way to limit the number of options the user can select in a multiple select html field like the one below?</p>
  
  <pre><code>&lt;select multiple id="color" name="color" size=5&gt;
  &lt;option&gt;- Choose one -&lt;/option&gt;
  &lt;option value="blu"&gt;Blue&lt;/option&gt;
  &lt;option value="yel"&gt;Yellow&lt;/option&gt;
  &lt;option value="bla"&gt;Black&lt;/option&gt;
  &lt;option value="ora"&gt;Orange&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>Say I want to 'force' the user to select exactly two out of the four options. How would I do that?</p>