Regular expression to get a string between two strings in Javascript

javascript regex string
phil picture phil · Apr 13, 2011 · Viewed 415.7k times · Source

I have found very similar posts, but I can't quite get my regular expression right here.

I am trying to write a regular expression which returns a string which is between two other strings. For example: I want to get the string which resides between the strings "cow" and "milk".

My cow always gives milk

would return

"always gives"

Here is the expression I have pieced together so far:

(?=cow).*(?=milk)

However, this returns the string "cow always gives".

Answer

R. Martinho Fernandes picture R. Martinho Fernandes · Apr 13, 2011

A lookahead (that (?= part) does not consume any input. It is a zero-width assertion (as are boundary checks and lookbehinds).

You want a regular match here, to consume the cow portion. To capture the portion in between, you use a capturing group (just put the portion of pattern you want to capture inside parenthesis):

cow(.*)milk

No lookaheads are needed at all.

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