Form validation of numeric characters in JavaScript

Question

I would like to perform form validation using JavaScript to check for input field only to contain numeric characters.So far, the validation checks for the field not being empty - which works fine.However, numeric characters validation is not working.I would be grateful for any help.Many thanks.

<script type="text/javascript">
//form validation
function validateForm()
{
var x=document.forms["cdp_form"]["univer_number"].value
if (x==null || x=="")
  {
  alert("University number (URN) field must be filled in");
  cdp_form.univer_number.focus();
  return false;
  }
else if (is_valid = /^[0-9]+$/.test(x))
    {
    alert("University number (URN) field must have numeric characters");
    cdp_form.univer_number.focus();
    return false;
  }
}
</script>


<input type ="text" id="univer_number" maxlength="7"    size="25"   name="univer_number" />

"Not working" is a poor way to describe a problem. What is not working? Are you getting errors? — Oded
– Oded, Commented Apr 26, 2011 at 19:48
It doesn't provide validation error which I wanted. Don't worry the problem has been solved - see accepted answer. — Igor Novoselov
– Igor Novoselov, Commented Apr 26, 2011 at 20:03
I worry, as I hope your next questions have better descriptions. tinyurl.com/so-hints — Oded
– Oded, Commented Apr 26, 2011 at 20:06

Mikecito · Accepted Answer · 2011-04-26 19:52:23Z

2

Rather than using Regex, if it must only be numerals you can simply use IsNumeric in Javascript.

IsNumeric('1') => true; 
IsNumeric('145266') => true;
IsNumeric('abc5423856') => false;

answered Apr 26, 2011 at 19:52

Mikecito

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Egor · Accepted Answer · 2011-04-26 19:53:33Z

2

You need invert your regular expression (add ^ inside [0-9]):

/^[^0-9]+$/

answered Apr 26, 2011 at 19:53

Egor

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Comments

Community · Accepted Answer · 2017-05-23 11:59:41Z

2

Your test condition is a bit strange:

else if (is_valid = /^[0-9]+$/.test(x))

Why have the redundant comparison to is_valid? Just do:

else if (/^[0-9]+$/.test(x))

Though the regex you are using will match numerals and only numerals - you need to change it to match anything that is not a numeral - like this /^[^0-9]+$/.

Better yet, get rid of the regex altogether and use IsNumeric:

else if (!IsNumeric(x))

edited May 23, 2017 at 11:59

CommunityBot

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answered Apr 26, 2011 at 19:50

Oded

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Donnie · Accepted Answer · 2011-04-26 19:50:46Z

1

On your line that says else if (is_valid = /^[0-9]+$/.test(x)), you're doing a simple assignment instead of testing that it is actually matching the regex.

answered Apr 26, 2011 at 19:50

Donnie

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1 Comment

Demian Brecht Over a year ago

As strange as it seems, it still yields the correct result (at least fiddling in chrome)

Papershine · Accepted Answer · 2018-02-19 05:25:36Z

1

Your pattern will still accept this input <b>#@$@#123 or ad!@#12<b>. Use this pattern I created:

/[a-zA-Z-!@#$%^&*()_+\=\[\]{};':"\\|,.<>\/?]/

This pattern will check if it is alphabetic and special characters.

edited Feb 19, 2018 at 5:25

Papershine

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answered Feb 19, 2018 at 5:22

Don

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Comments

mVChr · Accepted Answer · 2011-04-26 19:52:04Z

0

You need to test for the negation of the RegExp because you want the validation to alert upon failure, so just add ! in front of it:

else if (is_valid = !/^[0-9]+$/.test(x))

See example →

answered Apr 26, 2011 at 19:52

mVChr

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1 Comment

Igor Novoselov Over a year ago

Many thanks for your answer.It works - very easy to overlook such a mistake.

karthikr · Accepted Answer · 2013-03-28 19:44:01Z

0

I know this is an old post but I thought I'd post what worked for me. I don't require the field to be filled at all but if it is it has to be numerical:

function validateForm()
{
 var x=document.forms["myformName"]["myformField"].value;

if (/[^0-9]+$/.test(x))
    {
    alert("Please enter a numerical amount without a decimal point");
    myformName.myformField.focus();
    return false;
  } 
}

edited Mar 28, 2013 at 19:44

karthikr

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answered Mar 28, 2013 at 19:26

Dorothy Kerrin Ryan

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