window.onload = function() {
var myform = document.getElementById('regform');
var myformInputs = myform.getElementsByTagName('input');
	for (var i = 0;i < myformInputs.length; i++) {
			myformInputs[i].onblur = function () { checkField(this);};
			myformInputs[i].onfocus = function () { popupRemove(this);};
			} 
		myform.onsubmit = function() {return checkForm(this);};
}
	
function checkForm (el) {
		for (var i = 0;i < el.getElementsByTagName('input').length; i++) {
			if (el.getElementsByTagName('input')[i].value == '') {
			document.getElementById('helper').innerHTML = 'Please fill in all of the fields.';
			return false;
			}
		}
	}
function popupCreate(input) {
		var popup = document.createElement('p');
		popup.className = 'popup';
		popup.innerHTML = 'Please fill in this field!';
		input.parentNode.appendChild(popup);
	}
	
function popupRemove(input) {
	if(input.parentNode.getElementsByTagName('p').length == 1) {
		input.parentNode.removeChild(input.parentNode.lastChild);
		}
	}
	
function checkField(field) {
		if((field.value == '') && (field.parentNode.getElementsByTagName('p').length == 0)) { 
			popupCreate(field)
		} 
		else  {
			popupRemove(field);
		}
	}