只匹配一个引号

Question

I want to match three cases. Two quotation marks, quotation mark on the left, and quotation mark on the right:

/(?<=["])(.*?)(?=["])/g // "Dialogue."
/(?<=["])(.*?)(?!["])/g // "Dialogue.
/(?<!["])(.*?)(?=["])/g // Dialogue."

The regexes for matching only one quotation mark aren't matching anything:

https://regexr.com/5sd5u

Why is this and, how to fix it?

Answer 1

I want to match three cases. Two quotation marks, quotation mark on the left, and quotation mark on the right:

You can use this simplified approach using alternation:

^(?:"[^"]*"?|[^"]*")$

RegEx Demo

RegEx Details:

• ^ : Start
• (?: : Start non-capture group
  • " : Match a "
  • [^"]* : Match 0 or more of any character that is not "
  • "? : Match an optional last "
  • | : OR
  • [^"]* : Match 0 or more of any character that is not "
  • " : Match a "
• ) : End non-capture group
• $ : End

Answer 2

You can use

^(?![^"](?:.*[^"])$)"?[^"]*"?$

See the regex demo .

Details :

• ^ - start of string
• (??[^"](:..*[^"])$) - a negative lookahead that fails the match if the first and last chars are not "
• "? - an optional "
• [^"]* - zero or more chars other than "
• "? - an optional "
• $ - end of string.