function changeImage(element, newImg) {
    if(document.images[element] && newImg) {
        document.images[element].src = newImg;
    }
}

function clearBox(box) {
	 if(box.value==box.defaultValue) {
	 	 box.value = "";
	 }
}

function initLinks() {
  for (i in document.links) {
    link = document.links[i];
    if (link.rel && link.rel.indexOf('external')!=-1) {
      link.onclick = onExternalLinkActivate;
      link.onkeypress = onExternalLinkActivate;
    }
  }
}

function onExternalLinkActivate() {
  window.open(this.href);
  return false;
}
window.onload = initLinks;

function validateEmptyField(element, niceName) {
	if(element.value == '') {
		alert(niceName + ' field cannot be empty.');
		element.style.border = '1px solid red';
		return false;
	}
	else {
		element.style.border = '';
		return true;
	}
}

function validateFieldLength(element, niceName) {
	var length = element.length;
	if(parseInt(length) < 16) {
		alert(niceName + 'should be atleast 16 characters.');
		element.style.border = '1px solid red';
		return false;
	}
	else {
		element.style.border = '';
		return true;
	}
}

function validateCheckBox(element) {
	if(element.checked == false) {
		alert('Please tick to accept our terms and conditions.');
		return false;
	}
	else {
		return true;
	}
}

$(document).ready(function(){
	$('form#step1').validate();
	$('form#step2').validate({
		rules: {
			cardnumber: {
				required: true,
				minlength: 16
			}
		}
	});
});