Regular expressions
Regular expressions describe text patterns for search and replace. This syntax works in JavaScript, Python, PHP, Java, VS Code and most other tools.
Nothing matches your search.
Characters
- Any character except a new line
- A digit 0–9 (\D: anything but a digit)
- A letter, digit or _ (\W: anything else)
- Whitespace: space, tab, new line (\S: anything else)
- A real dot: put \ before . * + ? ( ) [ ] { } ^ $ | \
- New line (\t: tab)
Character classes
- a, b or c
- Anything except a, b or c
- Any lowercase letter
- Any letter or digit
- A dash or a dot (no escaping needed inside [ ])
Anchors
- Start of the text (or line, with the m flag)
- End of the text (or line, with the m flag)
- Word boundary: \bcat\b matches “cat” but not “catalog”
Quantifiers
- 0 or more
- 1 or more
- 0 or 1 (optional)
- Exactly 3
- 2 to 5
- 2 or more
- As few as possible (lazy); works after * + ? {}
Groups and alternatives
- Group, and remember the match as $1 / \1
- Group without remembering
- Named group
- cat or dog
- Back-reference: the same letter twice
Lookarounds
- a followed by b (b is not part of the match)
- a not followed by b
- Digits right after a $ sign
- Digits not right after a minus
Flags
- Global: find every match, not just the first
- Ignore upper/lower case
- Multi-line: ^ and $ work per line
- Dot also matches new lines
- Unicode: emoji and accented letters count as one character
Handy patterns
- Looks like an email address
- A web address
- A date like 2026-10-18
- A hex color like #0b6a8a
- A phone number (loose)
- Spaces at the start or end (replace with nothing to trim)
- Two or more spaces in a row