Choose particular content enclosed by two strings (across multiple lines)

Question

Choose particular content enclosed by two strings (across multiple lines)

Looking to use regex to extract specific text between two strings.

For example:

foo I have four toys bar    //single line

foo     //multiline
I
have
four
toys
bar

foo I have three pets bar

foo
I
have
three
pets bar

How can I extract the text between "foo" and "bar" that contains the word "four"?

Desired output:

I have four toys

I
have
four
toys

Here is my current regex code:

foo[\s\S]*?(four)[\s\S]*?bar

While this code works, it selects all text until the word "four" even if it's not within the "foo" and "bar" boundaries

foo I have three pets bar

foo I have four toys bar

foo
I
have
three
pets bar

My goal is to only extract text between "foo" and "bar" when it includes the word "four"

javascript regex regex-lookarounds regex-greedy

Answer 1

Answer №1

Here is a helpful regex pattern that can be used in dot all mode:

\bhello\s+(?:(?!\bworld\b).)*?\s+goodbye\s+(?:(?!\bhello\b).)*?\s+world

var input = `hello I have goodbye options world

hello
I
have
goodbye
options
world

hello I have no goodbye idea world

hello
I
have
no
goodbye
idea world`;

var matches = input.match(/\bhello\s+(?:(?!\bworld\b).)*?\s+goodbye\s+(?:(?!\bhello\b).)*?\s+world/gs)
                   .map(x => x.replace(/^hello\s+|\s+world$/g, ""));
console.log(matches);

An explanation of this elaborate regex pattern could be beneficial:

\bhello\s+          match 'hello' followed by one or more whitespace characters
(?:(?!\bworld\b).)*?  match any content WITHOUT encountering 'world'
\s+goodbye\s+        match 'goodbye' surrounded by whitespace
(?:(?!\bhello\b).)*?  match any content WITHOUT encountering 'hello'
\s+world            whitespace followed by ending 'world'

It's important to note that the match() method requires a map step to remove leading hello and trailing world from each match.

Answer 2

Here is a helpful regex pattern that can be used in dot all mode:

\bhello\s+(?:(?!\bworld\b).)*?\s+goodbye\s+(?:(?!\bhello\b).)*?\s+world

var input = `hello I have goodbye options world

hello
I
have
goodbye
options
world

hello I have no goodbye idea world

hello
I
have
no
goodbye
idea world`;

var matches = input.match(/\bhello\s+(?:(?!\bworld\b).)*?\s+goodbye\s+(?:(?!\bhello\b).)*?\s+world/gs)
                   .map(x => x.replace(/^hello\s+|\s+world$/g, ""));
console.log(matches);

An explanation of this elaborate regex pattern could be beneficial:

\bhello\s+          match 'hello' followed by one or more whitespace characters
(?:(?!\bworld\b).)*?  match any content WITHOUT encountering 'world'
\s+goodbye\s+        match 'goodbye' surrounded by whitespace
(?:(?!\bhello\b).)*?  match any content WITHOUT encountering 'hello'
\s+world            whitespace followed by ending 'world'

It's important to note that the match() method requires a map step to remove leading hello and trailing world from each match.

Choose particular content enclosed by two strings (across multiple lines)

Answer №1

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