Regex match overlap/crossover

Question

I need to capitalise acronyms in some text.

I currently have this regex to match on the acronyms:

/(^|[^a-z0-9])(ECU|HVAC|ABS|ESC|EGR|ADAS|HEV|HMI)($|[^a         


        

Answer 1

Yes the reason is because it overlaps (when matching the abs, it also consumes the /. Then for esc, it cannot find [^a-z0-9] because the next letter it is scanning is e).

You could use this RegEx instead:

\b(ECU|HVAC|ABS|ESC|EGR|ADAS|HEV|HMI)\b

\b is a Word Boundary, it does not consume any characters and therefore there will be no overlap

Live Demo on Regex101

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You can also change your RegEx to use a Positive Lookahead, since this also does not consume characters:

(^|[^a-z0-9])(ECU|HVAC|ABS|ESC|EGR|ADAS|HEV|HMI)(?=$|[^a-z0-9])

Live Demo on Regex101