Python regex alphanumeric and dash

Trying to check input against a regular expression.

The field should only allow alphanumeric characters, dashes and underscores and should NOT allow spaces.

However, the code below allows spaces.

What am I missing?

var regexp = /^[a-zA-Z0-9\-\_]$/;
var check = "checkme";
if (check.search(regexp) == -1)
    { alert('invalid'); }
else
    { alert('valid'); }

Donald Duck

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asked May 4, 2011 at 17:50

1

However, the code below allows spaces.

No, it doesn't. However, it will only match on input with a length of 1. For inputs with a length greater than or equal to 1, you need a + following the character class:

var regexp = /^[a-zA-Z0-9-_]+$/;
var check = "checkme";
if (check.search(regexp) === -1)
    { alert('invalid'); }
else
    { alert('valid'); }

Note that neither the - (in this instance) nor the _ need escaping.

bugwheels94

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answered May 4, 2011 at 17:54

Andy EAndy E

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0

This is the most concise syntax I could find for a regex expression to be used for this check:

const regex = /^[\w-]+$/;

answered Dec 14, 2017 at 2:19

Grant HumphriesGrant Humphries

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2

You shouldn't use String.match but RegExp.prototype.test (i.e. /abc/.test("abcd")) instead of String.search() if you're only interested in a boolean value. You also need to repeat your character class as explained in the answer by Andy E:

var regexp = /^[a-zA-Z0-9-_]+$/;

answered May 4, 2011 at 18:18

saphtsapht

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1

Got stupid error. So post here, if anyone find it useful

1. [-\._] - means hyphen, dot and underscore
2. [\.-_] - means all signs in range from dot to underscore

answered Jul 18, 2016 at 12:33

Ivan IvanovIvan Ivanov

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1

Try this

"[A-Za-z0-9_-]+"

Should allow underscores and hyphens

answered May 21, 2019 at 16:15

1

try this one, it is working fine for me.

"^([a-zA-Z])[a-zA-Z0-9-_]*$"

answered Oct 14, 2019 at 9:23

Don't escape the underscore. Might be causing some whackness.

answered May 4, 2011 at 17:52

David FellsDavid Fells

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2

Is dash included in alphanumeric?

What is dash in regex?

How do I enable hyphens in regex?

How do you match a space in regex?