Match content between two delimiters with regex
Extract text between <code>BEGIN</code> and <code>END</code> markers, or between brackets, or between any pair of delimiters. Quick regex recipe.
The basic pattern
/BEGIN([\s\S]*?)END/The lazy *? stops at the first END after a BEGIN. The capture group contains what was in between.
Use [\s\S] instead of . if the content might span multiple lines (no need for the s/dotall flag this way).
Between specific symbols
// Between brackets [content]
/\[([^\]]*)\]/
// Between curly braces {content}
/\{([^}]*)\}/
// Between parentheses (content) — careful with nesting
/\(([^)]*)\)/
// Between two underscores _content_ (Markdown italic)
/_([^_]+)_/Using a negated class [^X] works when the inner content can't contain X. For nested brackets, you need a parser, not regex.
Capture multiple occurrences
const text = "First [foo] then [bar] and [baz].";
const matches = [...text.matchAll(/\[([^\]]+)\]/g)];
matches.forEach(m => console.log(m[1]));
// "foo"
// "bar"
// "baz"Greedy vs lazy
Watch the difference:
// Greedy — grabs as much as possible
"[a][b][c]".match(/\[(.+)\]/)?.[1]; // "a][b][c"
// Lazy — grabs as little as possible
"[a][b][c]".match(/\[(.+?)\]/)?.[1]; // "a"For finding one occurrence at a time, lazy is usually what you want. For greedy "everything between the first and last delimiter", drop the ?.
Python
import re
BETWEEN_RE = re.compile(r"BEGIN(.*?)END", re.DOTALL)
for m in BETWEEN_RE.finditer(text):
print(m.group(1))For real nested content, use a parser
If you need to match balanced parens or nested HTML tags correctly, regex won't do it (except in PCRE/.NET with recursion). Use a real parser or a stack-based scan in code.