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

7,85120 gold badges70 silver badges91 bronze badges

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

29.4k3 gold badges37 silver badges59 bronze badges

answered May 4, 2011 at 17:54

Andy EAndy E

330k83 gold badges469 silver badges441 bronze badges

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

2,4461 gold badge22 silver badges24 bronze badges

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

2,67917 silver badges16 bronze badges

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

2,01717 silver badges30 bronze badges

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

6,5801 gold badge21 silver badges34 bronze badges

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?