function confirmClose() {

	if (arguments.length > 0) {
		for (var i = 0; i < arguments.length; i++) {
			this.forms_id.push(arguments[i]);
		}
	}
};

confirmClose.prototype = {
	prompt: 'You have unsaved changes.',
	forms_id: new Array(),
	forms: new Array(),
	formSubmit: false,

	getCurrentForms: function() {
		// Store current form's element's values

		var formsInPage = this.getForms();
		var f, e;
		var This = this;
		this.forms = new Array();
		for (var i = 0; i < formsInPage.length; i++) {
			f = formsInPage[i];
			var tmpForm = new Array();
			for (var j = 0; j < f.elements.length; j++) {
				e = this.getFormElementValue(f[j]);
				if (e != undefined) {
					tmpForm.push(e);
				}
			}
			this.forms.push(tmpForm);

			chainHandler(f, 'onsubmit', function() {
				This.formSubmit = true;
			});
		}
	},

	compareForms: function() {
		// Compare current form's element's values to their original values
		// Return false if any difference, else true

		if (this.forms.length == 0) {
			return true;
		}

		var formsInPage = this.getForms();
		var f, e;
		for (var i = 0; i < formsInPage.length; i++) {
			f = formsInPage[i];
			var tmpForm = new Array();
			for (var j = 0; j < f.elements.length; j++) {
				e = this.getFormElementValue(f[j]);
				if (e != undefined) {
					tmpForm.push(e);
				}
			}
			for (var j = 0; j < this.forms[i].length; j++) {
				if (this.forms[i][j] != tmpForm[j]) {
					return false;
				}
			}
		}

		return true;
	},

	getForms: function() {
		// Get current list of forms as HTMLCollection(s)

		if (!document.getElementsByTagName || !document.getElementById) {
			return new Array();
		}

		if (this.forms_id.length > 0) {
			var res = new Array();
			var f;
			for (var i = 0; i < this.forms_id.length; i++) {
				f = document.getElementById(this.forms_id[i]);
				if (f != undefined) {
					res.push(f);
				}
			}
			return res;
		} else {
			return document.getElementsByTagName('form');
		}

		return new Array();
	},

	getFormElementValue: function(e) {
		// Return current value of an form element

		if (e == undefined) {
			// Unknown object
			return undefined;
		}
		if (e.type != undefined && e.type == 'button') {
			// Ignore button element
			return undefined;
		}
		if (e.classList.contains('meta-helper') || e.classList.contains('checkbox-helper')) {
			// Ignore some application helper element
			return undefined;
		}
		if (e.type != undefined && e.type == 'radio') {
			// Return actual radio button value if selected, else null
			return this.getFormRadioValue(e);
		} else if (e.type != undefined && e.type == 'checkbox') {
			// Return actual checkbox button value if checked, else null
			return this.getFormCheckValue(e);
		} else if (e.type != undefined && e.type == 'password') {
			// Ignore password element
			return null;
		} else if (e.value != undefined) {
			// Return element value if not undefined
			return e.value;
		} else {
			// Every other case, return null
			return null;
		}
	},

	getFormCheckValue: function(e) {
		if (e.checked) {
			return e.value;
		}
		return null;
	},

	getFormRadioValue: function(e) {
		for (var i = 0; i < e.length; i++) {
			if (e[i].checked) {
				return e[i].value;
			} else {
				return null;
			}
		}
		return null;
	}
};

var confirmClosePage = new confirmClose();

chainHandler(window, 'onload', function() {
	confirmClosePage.getCurrentForms();
});

chainHandler(window, 'onbeforeunload', function(event_) {
	if (event_ == undefined && window.event) {
		event_ = window.event;
	}

	if (!confirmClosePage.formSubmit && !confirmClosePage.compareForms()) {
		event_.returnValue = confirmClosePage.prompt;
		return confirmClosePage.prompt;
	}
	return false;
});