var plzfield = document.getElementsByName('plz_adresse');

if (plzfield.length > 0)
{
	for (var i = 0; i < plzfield.length; i++)
	{
		if (plzfield[i].attachEvent)
		{
			plzfield[i].attachEvent('onkeyup', plzsearchcheckform);
		}
		else
		{
			plzfield[i].addEventListener('keyup', plzsearchcheckform, true);
		}
	}
}

function plzsearchcheckform(e)
{
	if (e.srcElement)
	{
		var ele = e.srcElement;
	}
	else
	{
		var ele = e.target;	
	}
	
	var newtext = '';
	for (var i = 0; i < ele.value.length; i++)
	{
		if (ele.value.charCodeAt(i) >= 48 && ele.value.charCodeAt(i) <= 57)
		{
			newtext += ele.value.substr(i, 1);
		}
	}
	ele.value = newtext;
	
	var securityout = 0;
	var formele = ele.parentNode;
	while (formele.tagName != 'FORM' && formele.tagName != 'BODY')
	{
		formele = formele.parentNode;
		securityout++;
		
		if (securityout >= 30)
		{
			break;
		}
	}
	
	if (securityout < 30 && formele.tagName == 'FORM')
	{
		var allinputs = formele.getElementsByTagName('INPUT');
		for (var i = 0; i < allinputs.length; i++)
		{
			if (allinputs[i].tagName == 'INPUT' && allinputs[i].type == 'submit')
			{
				if (ele.value.length >= 3)
				{
					allinputs[i].disabled = false;
					allinputs[i].className = allinputs[i].className.replace(/ submitdisabled/gi, '');
				}
				else
				{
					allinputs[i].disabled = true;
					allinputs[i].className += ' submitdisabled';
				}
				
				break;
			}
		}
	}
}