Nie wiem czemu ten kod nie dziala
<!DOCTYPE HTML>
<hmtl>
<head>
<meta charset="UTF-8">
<title>Przyklad</title>
</head>
<body>
<form method="post">
<input type="checkbox" id="terms" />
<div id="termsHint"></div>
<input type="submit" value="Zarejestruj sie" id="formSignup"/>
</form>
<script type="text/javascript">
var elForm, elTerms, elTermsHint;
elForm = document.getElementById("formSignup");
elTerms = document.getElementById("terms");
elTermsHint = document.getElementById("termsHint");
function checkTerms(event){
if(!elTerms.checked){
elTermsHint.innerHTML = "Musisz zgodzic sie z warunkiem!";
event.preventDefault();
}
}
elForm.addEventListener("submit",checkTerms, false);
</script>
</body>
</hmtl>