JavaScript: isNaN Function
isNaN Function :-
Evaluates an argument to determine if it is not a number.
Syntax :-
isNaN(value)
value = The value you want to evaluate.
Description :-
isNaN is a top-level function and is not associated with any object.
On platforms that support NaN, the parseFloat and parseInt functions return NaN when they evaluate a value that is not a number. isNaN returns true if passed NaN, and false otherwise.
Example:
<html>
<head>
<title>isNaN Fnction</title>
<script language="javascript">
function check()
{
var phone=f1.phone.value;
if(isNaN(phone))
alert("Characters are not allowed in the Phone Number");
else
alert("Your Phone Number is Accepted");
}
</script>
</head>
<body>
<form name="f1">
Phone: <input type="text" name="phone" size="20">
<input type="button" value="check" onclick="check()">
</form>
</body>
</html>
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trash...
ReplyDeletetrash
ReplyDeleteits a trash ....even null is accepted as a phone number
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ReplyDeletefunction check()
ReplyDelete{
var phone=f1.phone.value;
if(phone=="" || isNaN(phone))
alert("Please INput the correct formet Corrent formet is number");
else
alert("Your Phone Number is Accepted");
}
It will work for both null and Characters
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ReplyDelete