What does "isNaN" function do in Java Script? [Resolved]

Posted by Programmer123 under JavaScript on 9/24/2013 | Points: 10 | Views : 4571 | Status : [Member] | Replies : 5

Write New Post |

Search Forums | Answered

Resolved Posts |

Un Answered Posts |

Forums Home

What does "isNaN" function do in Java Script?

[Resolved]

Reply | Reply with Attachment

Alert Moderator

Responses

Posted by: Murugavelmsc on: 9/25/2013 [Member] Starter | Points: 50

0	The isNaN() function determines whether a value is an illegal number (Not-a-Number). This function returns true if the value is NaN, and false if not. Eg: <script> document.write(isNaN(123)+ "<br>"); document.write(isNaN(-1.23)+ "<br>"); document.write(isNaN(5-2)+ "<br>"); document.write(isNaN(0)+ "<br>"); document.write(isNaN("Hello")+ "<br>"); document.write(isNaN("2005/12/12")+ "<br>"); </script> Output: false false false false true true Regards, Murugavel S murugavel.sadagopan@gmail.com http://murugavelmsc.blogspot.in/ Programmer123, if this helps please login to Mark As Answer. \| Alert Moderator

The isNaN() function determines whether a value is an illegal number (Not-a-Number).

This function returns true if the value is NaN, and false if not.

Eg:

<script>

document.write(isNaN(123)+ "<br>");
document.write(isNaN(-1.23)+ "<br>");
document.write(isNaN(5-2)+ "<br>");
document.write(isNaN(0)+ "<br>");
document.write(isNaN("Hello")+ "<br>");
document.write(isNaN("2005/12/12")+ "<br>");

</script>

Output:
false
false
false
false
true
true

Regards,
Murugavel S
murugavel.sadagopan@gmail.com
http://murugavelmsc.blogspot.in/

Programmer123, if this helps please login to Mark As Answer. | Alert Moderator

Posted by: Bandi on: 9/25/2013 [Member] [MVP] Platinum | Points: 25

0	. The isNaN() function determines whether a value is an illegal number (Not-a-Number). . Evaluates an argument to determine if it is not a number. Syntax :- isNaN(value) value = The value you want to evaluate. Sample: <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> To check that a number is NaN in JavaScript: isNaN(parseFloat("VariableName")) If VariableName is float/int then returns true; else false Mark This Response as Answer -- Chandu http://www.dotnetfunda.com/images/dnfmvp.gif Programmer123, if this helps please login to Mark As Answer. \| Alert Moderator

*. The isNaN() function determines whether a value is an illegal number (Not-a-Number).
*. Evaluates an argument to determine if it is not a number.

Syntax :-

isNaN(value)
value = The value you want to evaluate.

Sample:

<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>

To check that a number is NaN in JavaScript:

isNaN(parseFloat("VariableName"))

If VariableName is float/int then returns true; else false

Mark This Response as Answer
--
Chandu
http://www.dotnetfunda.com/images/dnfmvp.gif

Programmer123, if this helps please login to Mark As Answer. | Alert Moderator

Posted by: Bandi on: 9/25/2013 [Member] [MVP] Platinum | Points: 25

0	isNaN Function Returns a Boolean value that indicates whether a value is the reserved value NaN (not a number). isNaN(numValue) Return Value: true if the value converted to the Number type is the NaN, otherwise false. Points: 1) The required numValue is the value to be tested against NaN. 2) You typically use this method to test return values from the parseInt and parseFloat methods. 3) Alternatively, a variable that contains NaN or another value could be compared to itself. If it compares as unequal, it is NaN. This is because NaN is the only value that is not equal to itself. Examples: // Returns false. isNaN(100); // Returns false. isNaN("100"); // Returns true. isNaN("ABC"); // Returns true. isNaN("10C"); // Returns true. isNaN("abc123"); // Returns true. isNaN(Math.sqrt(-1)); Mark This Response as Answer -- Chandu http://www.dotnetfunda.com/images/dnfmvp.gif Programmer123, if this helps please login to Mark As Answer. \| Alert Moderator

isNaN Function
Returns a Boolean value that indicates whether a value is the reserved value NaN (not a number).

isNaN(numValue)

Return Value: true if the value converted to the Number type is the NaN, otherwise false.

Points:
1) The required numValue is the value to be tested against NaN.
2) You typically use this method to test return values from the parseInt and parseFloat methods.
3) Alternatively, a variable that contains NaN or another value could be compared to itself. If it compares as unequal, it is NaN. This is because NaN is the only value that is not equal to itself.

Examples:


// Returns false.
isNaN(100);

// Returns false.
isNaN("100");

// Returns true.
isNaN("ABC");

// Returns true.
isNaN("10C");

// Returns true.
isNaN("abc123");

// Returns true.
isNaN(Math.sqrt(-1));

Mark This Response as Answer
--
Chandu
http://www.dotnetfunda.com/images/dnfmvp.gif

Programmer123, if this helps please login to Mark As Answer. | Alert Moderator

Posted by: Allemahesh on: 9/25/2013 [Member] [MVP] Silver | Points: 25

0	It returns true if the argument is not a number. B]Example: CODE]document.write(isNaN("Hello")+ "<br>"); document.write(isNaN("2013/06/23")+ "<br>"); document.write(isNaN(123)+ "<br>"); OutPut:- true true false Happy Coding, If it helps you or directs U towards the solution, MARK IT AS ANSWER Programmer123, if this helps please login to Mark As Answer. \| Alert Moderator

Posted by: aswinialuri-19361 on: 9/25/2013 [Member] Starter | Points: 25

0	hi, NaNfunction-Not a number or illegal number <script> document.write(isNaN(0)+ "<br>"); o/p:false document.write(isNaN("Hello")+ "<br>"); o/p:true document.write(isNaN("2005/12/12")+ "<br>"); o/p:true </script> Mark as Answer if it helps you Thanks&Regards Aswini Aluri Programmer123, if this helps please login to Mark As Answer. \| Alert Moderator

Latest Posts