Is there a way to limit the number of options the user can select in a multiple select html field like the one below?
<select multiple id="color" name="color" size=5>
<option>- Choose one -</option>
<option value="blu">Blue</option>
<option value="yel">Yellow</option>
<option value="bla">Black</option>
<option value="ora">Orange</option>
</select>
Say I want to 'force' the user to select exactly two out of the four options. How would I do that?