function get(id) {
	if(document.getElementById(id)) {
		return document.getElementById(id);
	}
	return false;
}

function changeValue(check,checkValue,insertValue) {
	if(get(check)) {
		if(get(check).value==checkValue) {
			get(check).value=insertValue;
		}
		return true;
	}
	return false;
}

function replace(check,checkValue,insertValue) {
	if(get(check)) {
		get(check).value=get(check).value.replace(checkValue,insertValue);
		return true;
	}
	return false;
}

function change(id,action,insertValue) {
	if(get(id)) {
		switch(action) {
			case 'action': get(id).action=insertValue; break;
			case 'style.background': get(id).style.background=insertValue; break;
			case 'style.border': get(id).style.border=insertValue; break;
			case 'checked': get(id).checked=insertValue; break;
			case 'disabled': get(id).disabled=insertValue; break;
			case 'html': get(id).innerHTML=insertValue; break;
			default: get(id).value=insertValue; break;
		}
		return true;
	}
	return false;
}

function style(id,action,insertValue,checkValue) {
	if(get(id)) {
		if(checkValue==0) {
			switch(action) {
				case 'display': get(id).style.display=insertValue; break;
			}
			return true;
		}
		else {
			switch(action) {
				case 'display': get(id).style.display==checkValue?style(id,action,insertValue,0):style(id,action,checkValue,0); break;
			}
			return true;
		}
	}
	return false;
}

function checkAll() {
	var i=0;
	if(get('check_all').checked==true) {
		while(change('check_' + i++,'checked',true));
	}
	else {
		while(change('check_' + i++,'checked',false));
	}
}

function alert1() {
	alert("Nie uzupełniono wszystkich wymaganych pól!!!");
}

<!-- aktualności: sprawdzanie checkboxa -->

function checkIfActiv(id,check1,check2) {
	if(document.getElementById(id).checked == true) {
		document.getElementById(check1).disabled = true;
		document.getElementById(check1).value = '';
		document.getElementById(check2).disabled = true;
		document.getElementById(check2).value = '';
	} else {
		document.getElementById(check1).disabled = false;
		document.getElementById(check2).disabled = false;
		document.getElementById('calendar1').disabled = false;
		document.getElementById('calendar2').disabled = false;
	}
}

function dodaj_zero(liczba)
	{
	if(liczba<10) return "0"+liczba;
		else return liczba;
	}