var default_val_search_field = 'Vul uw zoekterm in';
$(document).ready(function() {
	  $('input.search_field').click(function() {
		if($('input.search_field').val()==default_val_search_field){
			$('input.search_field').val('');
		}
	});
	$('input.search_field').blur(function () {
		if($('input.search_field').val()==''){
			$('input.search_field').val(default_val_search_field);
		}
	});
	if($('input.search_field').val()==''){
		$('input.search_field').val(default_val_search_field);
	}
});