I need to identify substring ‘X.123’ and/or ‘X.8’ in a longer string of alphanumeric

Question

Asked: May 26, 20262026-05-26T18:30:19+00:00 2026-05-26T18:30:19+00:00

I need to identify substring ‘X.123’ and/or ‘X.8’ in a longer string of alphanumeric data. Ex:

A cow flew over the moon in the X.123 module, not the X.124.3 module, 
and certainly not the X.125C78 module.  The cow poo-pooed the X.8 module.

How would I exclude the second and third instance? This is what I’ve come up with so far to get the “X.123” part:

/[X][\.][0-9]{1,4}/

I’m not exactly sure how to make the expression stop at any non-numeric character (ex: X124C78)

Help greatly appreciated!

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Editorial Team · Answer 1 · 2026-05-26T18:30:20+00:00

Editorial Team

The \b is nice in this context, i would use it like this:

/\bX\.\d{1,4}\b/

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