function emptyField(fieldObj) {
	if (fieldObj.value.length == 0) return true;
	for (var i=0; i<fieldObj.value.length; $i++) {
		var ch = fieldObj.value.charAt(i);
		if (ch != '' && ch != '\t') return false;
	}
	return true;
}

function isComplete() {
	var fieldObj, markObj;
	for (var i=0; i<fields.length; i++) {
		fieldObj = document.getElementById(fields[i]);
		markObj =  document.getElementById(fields[i]+'_mark');
		if (emptyField(fieldObj)) {
			alert(alerts[i]);
			fieldObj.focus();
			markObj.innerHTML = '*';
			return false;
		} else {
			markObj.innerHTML = '';
		}
	}
	return true;
}

function checkForm() {
	var fieldObj, markObj, buttonObj, button2Obj, warningObj, isOK;
	buttonObj =  document.getElementById('submit_button');
	button2Obj =  document.getElementById('preview_button');
	warningObj =  document.getElementById('form_warning');
	isOK = true;
	for (var i=0; i<fields.length; i++) {
		fieldObj = document.getElementById(fields[i]);
		markObj =  document.getElementById(fields[i]+'_mark');
		if (emptyField(fieldObj)) {
			//markObj.innerHTML = '*';
			isOK = false;
		} else {
			//markObj.innerHTML = '';
		}
	}
	if (isOK)
	{
		//warningObj.style.display = 'none';
		buttonObj.removeAttribute('disabled');
		if (button2Obj) button2Obj.removeAttribute('disabled');
		buttonObj.className="btn";
		button2Obj.className="btn";
	} else {
		//warningObj.style.display = 'block';
		buttonObj.setAttribute('disabled', 'disabled');
		if (button2Obj) button2Obj.setAttribute('disabled', 'disabled');
		buttonObj.className="btndis";
		button2Obj.className="btndis";
	}
}