Is there any simple method in JavaScript / jQuery to check whether the variable is a number or not (preferably without a plugin)? I want to alert whether the variable is a number or not.
Thanks in advance...:)
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stackoverflow.com/questions/995183/…Amr Elgarhy– Amr Elgarhy2011-04-14 12:31:21 +00:00Commented Apr 14, 2011 at 12:31
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no.. This is not the repeat of the question mentioned. I am looking to validate without a plugin..Alfred– Alfred2011-04-14 13:34:54 +00:00Commented Apr 14, 2011 at 13:34
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1do accpet ans if it work for youPranay Rana– Pranay Rana2011-04-21 07:12:28 +00:00Commented Apr 21, 2011 at 7:12
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5 Answers
I wouldn't recommend the isNaN function to detect numbers, because of the Java Script type coercion.
Ex:
isNaN(""); // returns false (is number), a empty string == 0
isNaN(true); // returns false (is number), boolean true == 1
isNaN(false); // returns false (is number), boolean false == zero
isNaN(new Date); // returns false (is number)
isNaN(null); // returns false (is number), null == 0 !!
You should also bear in mind that isNaN will return false (is number) for floating point numbers.
isNaN('1e1'); // is number
isNaN('1e-1'); // is number
I would recommend to use this function instead:
function isNumber(n) {
return !isNaN(parseFloat(n)) && isFinite(n);
}
6 Comments
Alfred
so what are yo trying to say, do i modify @Pranay Rana's answer??
Corneliu
I was just trying to say that using isNaN function is not the most "correct" way to check if a string is a number in Java Script.
Alfred
is there any other simple way?? can u make me a fiddle?? :)
Corneliu
You don't like the function I have sugested to use in the answer?
Alfred
I like.. Can u demonstrate it with a fiddle??
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Checking number using isNaN function
var my_string="This is a string";
if(isNaN(my_string)){
document.write ("this is not a number ");
}else{document.write ("this is a number ");
}
or
Check whether a number is an illegal number:
<script type="text/javascript">
document.write(isNaN(5-2)+ "<br />");
document.write(isNaN(0)+ "<br />");
document.write(isNaN("Hello")+ "<br />");
document.write(isNaN("2005/12/12")+ "<br />");
</script>
The output of the code above will be:
false
false
true
true
1 Comment
Alfred
hello @Pranay Rana, can u demonstrate it in a fiddle??
Can use below code for this. I would not rely on isNaN() completely. isNaN has shown inconsistent results to me (e.g - isNaN will not detect blank spaces.).
//Event of data being keyed in to textbox with class="numericField".
$(".numericField").keyup(function() {
// Get the non Numeric char that was enetered
var nonNumericChars = $(this).val().replace(/[0-9]/g, '');
if(nonNumericChars.length > 0)
alert("Non Numeric Data entered");
});
4 Comments
amphetamachine
Good point, but what happens when the user deletes all the characters in the input?
Mrinal Jha
nonNumericChars.length will still be zero and the alert will not be thrown. Are you looking for anything else to do with tat event?
amphetamachine
Ah, you're right. I thought I had caught you with an error, but it turns out I was wrong. I like your answer.
Mrinal Jha
Thats ok. Best part is we can always some way to fix all errors. so if you can find errors, its better I will learn more :)
function isDigit(num) {
if (num.length>1){return false;}
var string="1234567890";
if (string.indexOf(num)!=-1){return true;}
return false;
}
You need to loop through the string and call this function for every character
Comments
use standard javascript functions
isNaN('9')// this will return false
isNaN('a')// this will return true
