alphanumeric javascript regex failing [duplicate]

Question

I am trying to interrupt a form submission to test field for alphanumeric characters. After googling i found a lot of this implementation for regex that everyone claims works great...

if( !jQuery('input[name=myUsername]').val().test(/^[a-zA-Z0-9]+/) ) {
        alert('ERROR: Your username contains invalid characters. Please use numbers and letters only. No spaces, no punctuation.');
        jQuery('input[name=myUsername]').focus();
        return false;
}

However, this ONLY returns false and creates an alert if the value STARTS with a non-alphanumeric character. If i enter "bo$$" it allows it as alphanumeric even tho $ is not an alphanumeric character... If i enter "$$ob" it fails and alerts.

How do i fix this so that it will fail for ANY invalid character in the entire value? I've tried .match() instead of .test() but same issue im assuming it's something in the regex that is wrong

try /^[a-zA-Z0-9]+$/

Pramod Karandikar
– Pramod Karandikar

2015-01-28 06:50:49 +00:00
Commented Jan 28, 2015 at 6:50 — Pramod Karandikar
– Pramod Karandikar, Commented Jan 28, 2015 at 6:50

vks · Accepted Answer · 2015-01-28 07:14:18Z

2

^[a-zA-Z0-9]+$

put $ the end anchor to limit that.Without $ your regex will make a partial match.

$ assert position at end of a line

bo$$ will make a partial match upto bo as $ is not there.

edited Jan 28, 2015 at 7:14

answered Jan 28, 2015 at 6:51

vks

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2 Comments

J Richard Snape Over a year ago

Don't normally compromise my anonymity on down votes, but in this case I'll make an exception although I'll delete the comment after a few hours. Downvote as the original was unclear / gave the wrong impression. Your edit then fixed it, so I have reversed the downvote.

J Richard Snape Over a year ago

Fair enough - I was rushing a bit. You're right - a comment is usually helpful / only fair.

anubhava · Accepted Answer · 2015-01-28 06:50:54Z

0

Use anchor $ to avoid matching unwanted character at the end:

/^[a-zA-Z0-9]+$/

answered Jan 28, 2015 at 6:50

anubhava

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