如何形成正则表达式以匹配所有内容到“（”

Question

In javascript, how can a regular expression be formed to match everything up to and NOT including an opening parenthesis "("?

example input:

"12(pm):00" "12(am):))" "8(am):00"

ive found /^(.*?)\\(/ to be successful with the "up to" part, but the match returned includes the "("

In regex101.com, its says the first capturing group is what im looking for, is there a way to return only the captured group?

Answer 1

There are three ways to deal with this. The first is to restrict the characters you match to not include the parenthesis:

 let match = "12(pm):00".match(/[^(]*/); console.log(match[0]);

The second is to only get the part of the match you are interested in, using capture groups:

 let match = "12(pm):00".match(/(.*?)\\(/); console.log(match[1]);

The third is to use lookahead to explicitly exclude the parenthesis from the match:

 let match = "12(pm):00".match(/.*?(?=\\()/); console.log(match[0]);

As in OP, note the non-greedy modifier in the second and third case: it is necessary to restrict the quantifier in case there is another open parenthesis further inside the string. This is not necessary in the first place, since the quantifier is explicitly forbidden to gobble up the parenthesis.

Answer 2

Try

^\d+

^ asserts position at start of a line

\\d matches a digit (equal to [0-9])

+ Quantifier — Matches between one and unlimited times, as many times as possible, giving back as needed (greedy)

https://regex101.com/r/C9XNT4/1