Submit Form with Enter Key

programming
1

Does anyone know how I can make the following work when I hit enter rather than only working when I click submit?

<form name="whoisForm" id="whoisForm" method="post" action="<?php echo $_SERVER['PHP_SELF']; ?>"
                                <input name="domainForm" type="text" id="domainForm" value="<?php showPrevious(); ?>" />
                                <select name="extForm" id="extForm">
                                  <?php /* This shows the domain extensions in the drop-down box. */ formExtensions(); ?>
                                </select>
                                <input name="submitForm" type="submit" id="submitForm" value="Check" />
                            </form></td>