How to not match given prefix in RegEx without negative lookbehind?

Question

Goal

The goal is matching a string in JavaScript without certain delimiters, ie a string between two characters (the characters can be included in the match).
For example, this string should be fully matched: $ test string $ . This can appear anywhere in a string. That would be trivial, however, we want to allow escaping the syntax, eg The price is 5\$ to 10\$ .

Summarized:

• Match any string that is enclosed by two $ signs.
• Do not match it if the dollar signs are escaped using \$ .

Solution using negative lookbehind

A solution that achieves this goal perfectly is: (?<.\\)\$(?*?)(?<!\\)\$ .

Problem

This solution uses negative lookbehind , which is not supported on Safari . How can the same matches be achieved without using negative lookbehind (ie on Safari)?

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A solution that partially works is (?<.\\)\$(?*?)(?<!\\)\$ . However, this will also match the character in front of the $ sign if it is not a \ .

Answer 1

You might rule out what you don't want by matching it, and capture what you want to keep in group 1

\\\$.*?\$|\$.*?\\\$|(\$.*?\$)

Regex demo

Answer 2

You may use this regex and grab your inner text using capture group #1 as you are already doing in your current regex using lookbehind:

(?:^|[^\\])\$((?:\\.|[^$])*)\$

RegEx Demo

RegEx Details:

• (?:^|[^\\]) : Match start position or a non-backslash character in a non-capturing group
• \$ : Match starting $
• ( : Start capturing group
  • (?:\\.|[^$])* : Match any escaped character or a non- $ character. Repeat this group 0 or more times
• ) : End capturing group
• \$ : Match closing $

PS: This regex will give same matches as your current regex: (?<.\\)\$(?*?)(?<!\\)\$