Javascript - Create Regex Character Class

Question

Is there a way to use javascript's regex engine to create a character class that matches with

" or " (one space before ") or . or , or [SM_l] or nothing (not the string "nothing" , just 0 characters)

Background Context: This is going to be used as part of the solution to solve the problem presented in this post: Javascript - how to use regex process the following complicated string

I have no clue on how to do this. This is part of a way to solve a different, larger, problem that I have already tried solving. I edited my post with context. — Foobar
– Foobar, Commented Apr 19, 2018 at 4:47
Isn't it the same issue as described in stackoverflow.com/questions/49912307/…? — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Apr 19, 2018 at 6:30
@WiktorStribiżew I didn't think it was the same thing - the previous post can have multiple different solutions. For example - I solved the previous problem with regex in a completely different manner, than the way I am describing here. — Foobar
– Foobar, Commented Apr 19, 2018 at 15:00

revo · Accepted Answer · 2018-04-19 07:15:27Z

1

You don't a character class. A character class [...] denotes a match on every individual unit of data in it by which["]+ means characters &, q, u, o, t or ; in any order, with or without all characters:

"
&uot;
;&

What you need is called grouping. You just need a | inside a grouping construct to imply OR conditions (that I also applied in an answer to your original question)

" or " (one space before ")

means [ ]?"

. or , or [SM_l]

means (\.|,|\[SM_l]) that could be reduced to ([.,]|\[SM_l])

Putting all together you need:

([ ]?&quot;|[.,]|\[SM_l])?

Question mark denotes an optional match.

answered Apr 19, 2018 at 7:15

revo

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2 Comments

Foobar Over a year ago

I noticed in your previous answer that you said ` ?"` instead of [ ]?quot; is there any real difference between the two, or is one better than the other?

revo Over a year ago

No there is no real difference. Literal spaces are vague inside code blocks. Hence, I used a character class to overcome this issue.

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