Javascript regular expression: match anything up until something (if there it exists)

Question

Hi I am new to regular expression and this may be a very easy question (hopefully).

I am trying to use one solution for 3 kind of string

• \"45%\", expected

Answer 1

I just wrote it exactly how you said it:

str.match(/(^[^%]*$)|^([^%]*)%.*/i)

This will match any string without a '%' or the first part of a string that contains a %. You have to get the result from the 1st or 2nd group.

EDIT: This is exactly what you want below

str.match(/(?:^[^%]*$)|^(?:[^%]*)(?=%)/)

• The ?: removes all grouping
• The ?= is a lookahead to see if the string contains %
• and [^%] matches any character that is not a %

so the regex reads match any string that doesnt contain %, OR (otherwise match) all of the characters before the first %