<!DOCTYPE html>
<html>
<body>
<form action="tryjs_submitpage.htm" onsubmit="return myFunction()">
Name (max 10 characters): <input type="text" id="fname" size="20"><br>
Age (from 1 to 100): <input type="text" id="age" size="20"><br>
E-mail: <input type="text" id="email" size="20"><br><br>
<input type="submit" value="Submit">
</form>
<script>
function myFunction() {
var at = document.getElementById("email").value.indexOf("@");
var age = document.getElementById("age").value;
var fname = document.getElementById("fname").value;
submitOK = "true";
if (fname.length > 10) {
alert("The name may have no more than 10 characters");
submitOK = "false";
}
if (isNaN(age) || age < 1 || age > 100) {
alert("The age must be a number between 1 and 100");
submitOK = "false";
}
if (at == -1) {
alert("Not a valid e-mail!");
submitOK = "false";
}
if (submitOK == "false") {
return false;
}
}
</script>
</body>
</html>