Some simple jQuery tricks and polyfills.

simple.js

$(function(){
	$('html').removeClass('no-js').addClass('js');
	
	$('[autofocus]').focus();
	
	if("placeholder" in document.createElement("input")) {
		$('html').addClass('placeholder');
	} else {
		$('html').addClass('no-placeholder');
	}
	
	if($('html').hasClass('no-placeholder')) {
		$('[data-placeholder]').each(function(){
			$(this).parents().first().prepend('<span class="label">'+$(this).attr('data-placeholder')+'</span>');
		});
	} else if ($('html').hasClass('placeholder')) {
		$('[data-placeholder]').each(function(){
			$(this).attr('placeholder',$(this).attr('data-placeholder'));
		});
	}
});