Write regular expression for repeated consecutive characters in a string

Question

Given a string, var str = "abcc", if var regExp = /(.)\1+/, then it successfully identify "cc" by running "abcc".match(regExp);, but why /.\1+/ not works since it also means more than one copies of the previous character? Please provide some insight?

https://regexper.com run them through this – Andrew Bone Feb 22 '18 at 14:49 — Andrew Bone, Feb 22 '18 at 14:49
Cool! I just tested the regular expression on it. – juanli Feb 22 '18 at 14:52 — juanli, Feb 22 '18 at 14:52

score 2 · Accepted Answer · answered Feb 22 '18 at 14:52

2

(.) denotes a capture group that is later referred to using \1, so basically you say "find multiple occurrences of capture group 1".

Your second example won't work because there is no capture group involved.

answered Feb 22 '18 at 14:52

Katajun

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I want to know why I have to use 'capture group' in this case to make it work. Does '/.\1+/' not indicate the repeated consecutive characters? I don't understand it. – juanli Feb 22 '18 at 14:55
I understand now. Thanks again. – juanli Feb 22 '18 at 15:03
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Without a capture group, `\1` is meaningless. If removed and left with `/.+/` (or even `/(.)+/`, this would simply mean "match one or more of any character" and would match any string longer than zero characters. – Katajun Feb 22 '18 at 15:04

Write regular expression for repeated consecutive characters in a string

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