正则表达式匹配以模式开头的字符

Question

Given the following setting:

• input = "window.addEventListener('click', (s, d) => {});"

• desired match = "(s, d) =>"

tried the regex

(.*).*=>

But this will match "('click', (s, d) =>" , which is not desired.

Any ideas on how to modify the regex so that the match only starts from the closest opening parentheses before the "=>" symbol?

Any help is much appreciated!

Answer 1

You may use this regex with re.findall :

>>> s = "window.addEventListener('click', (s, d) => {});"
>>> print (re.findall(r'\([^()]*\)\s*=>', s)[0])
(s, d) =>

RegEx Details:

• \\( : Match (
• [^()]* : Match 0 or more of any character that is not ( and )
• \\) : Match )
• \\s*=> : Match 0 or more whitespaces followed by text =>

Answer 2

this is what you need to use. lookbehind more precisely https://javascript.info/regexp-lookahead-lookbehind

Answer 3

(?<=\\().+(\\(.+\\).*=>)

See Regex101

Basically a lookbehind for the first open paren, and a capture group for the desired result.