Regular expressions·a comma left before a closing bracket

a comma left before a closing bracket

Matches a comma left before a closing bracket. It finds the match anywhere inside the text. There is 1 capture group.

Pattern
/,\s*([}\]])/
Match scope
anywhere inside the text
Capture groups
1
What it catches in the first example
,]

Try it yourself

Type any text and the parts this expression catches are highlighted. It runs in your browser and is never sent anywhere.

[1,2,] {"a":1, }

2 matches

Examples that match

  • [1,2,]
  • {"a":1, }

Examples that do not match

  • [1,2]
  • {"a":1}

Other expressions in this group

How to read this

  • With ^ and $ around it, the whole string must match; without them the match can sit anywhere. Always anchor an expression you use for validation.
  • Round brackets ( ) capture what they wrap. When you only need grouping, write (?: ) so the numbering of later groups does not shift.
  • Every expression here is checked against its examples. Even so, "looks like an email" and "is a real inbox" remain different questions.
  • Nested open-ended repeats such as (a+)+ can blow up on certain inputs. Look for that shape before pasting someone else’s expression into your code.

Frequently asked questions

Q. What is the regex for a comma left before a closing bracket?

,\s*([}\]]).

Q. Which strings match?

Text like [1,2,] matches; text like [1,2] does not.

Q. Does the whole string have to match?

No. It finds the part anywhere inside the text. Add ^ and $ around it if you want a whole-string check.

Q. How do I use what it caught?

There is one capture group, so you can read them from match[1] onwards.