Why does my pattern only show one match?

Without the g flag a regular expression stops at the first match. Turn g on to scan the whole string. The y flag is different again, it anchors every attempt at the end of the previous match, so a single non-matching character ends the run.

Regex Tester

No upload · runs in your browser

Pattern

//gm

Flags

Test string

Highlighted matches

Support tickets this week:

  [email protected] opened #412 (billing)
  [email protected] opened #413 (login)
  not-an-email@ opened #414, malformed, ignore
  [email protected] and [email protected] both replied

Matches

Unique

Capture groups

Characters matched

Match details

#	Index	Match	Groups
1	30	[email protected]	user: ada.lovelacedomain: example.com
2	79	[email protected]	user: sam+betadomain: dev.example.co.uk
3	175	[email protected]	user: gracedomain: example.org
4	197	[email protected]	user: jane.doedomain: mail.example.com

Cheat sheet

.any character except newline (any character at all with the s flag)

\d \w \sdigit, word character, whitespace

\D \W \Sthe negation of each of the above

[abc] [^abc]one of these characters / anything but these

a{2,5}between two and five of a

a* a+ a?zero or more, one or more, optional

a+?lazy, match as few as possible

^ $start and end of the string, or of a line with the m flag

\bword boundary

(abc)capture group, referenced later as \1

(?:abc)group without capturing

(?<year>\d{4})named capture group

a|beither a or b

(?=abc) (?!abc)lookahead: followed by / not followed by

(?<=abc) (?<!abc)lookbehind: preceded by / not preceded by

\. \$ \(escape a character that would otherwise be special

Patterns are compiled and run in your browser, no pattern or test text is uploaded.

How it works

Regex Tester : Live Match Highlighting and Capture Groups

Write a pattern, flip the flags, and watch every match light up in your test string as you type. Capture groups and named groups are broken out in a table underneath.

What this does

Every match lights up in the test string as you type the pattern
All six JavaScript flags as independent toggles, g, i, m, s, u, y
Match table giving the start index of each match alongside its capture groups
Named groups from (?<name>…) labelled by name rather than by number, read out of the pattern itself
Compile errors rewritten in plain English: “Nothing to repeat” explains which quantifier has nothing before it

FAQ

Your browser’s own RegExp, so what matches here is what Node and front-end code will do.

Atomic groups, possessive quantifiers, recursion, the \A and \z anchors and inline flag groups like (?i) are PCRE or Python extensions that JavaScript never implemented, so patterns using them are reported as invalid. Lookbehind is the one to watch: (?<=…) works in current browsers, but it only reached Safari in 2023, so a pattern that is perfectly valid in this box can still fail for some visitors to a site you ship it to.

Yes. Matching is capped at 5,000 matches over the first 200,000 characters of the test string, and the table renders the first 200 rows, but none of that limits backtracking. A nested quantifier such as (a+)+b against a long non-matching string can spin for a very long time inside one call to exec, and there is no way to interrupt it once it starts. Simplify the nesting rather than shortening the input.

Keep going