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 think this is what you're looking for:

/(?:(?!%).)*/

The . matches any character, but only after the negative lookahead, (?!%), confirms that the character is not %. Note that when the sentinel is a single character like %, you can use a negated character class instead, for example:

/[^%]*/

But for a multi-character sentinel like , you have to use the lookahead approach:

/(?:(?!).)*/i

This is actually saying "Match zero or more characters one at a time, but if the next character turns out to be the beginning of the sequence or , stop without consuming it".