Mega Code Archive
Global isNaN()
<![CDATA[
Syntax
isNaN(variable)
The isNaN() function is used to determine whether variable is a valid number.
<html>
<body>
<script lanuguage="JavaScript">
<!--
function checkNum(){
var n = document.form1.text1.value;
if(isNaN(n) == true){
alert("Your entry is not a number");
}else{
alert("Your entry is a number");
}
}
-->
</script>
<form name="form1">
Enter a number or character into the text box and then click the check value
button to verify if the input is a number.
<br><br>
<input type="text" name="text1" size=3>
<br><br>
<input type="button" value="Check value" onClick='checkNum()'>
<br>
</form>
</body>
</html>
]]>