How do I set g, i, m, s and u flags?

Use the visible checkboxes. You do not need to put /pattern/flags on the first input line.

Why does Replace mode replace every match?

Replace mode ensures global replacement. The replacement supports group-reference syntax from browser RegExp.replace.

EffiRoom

Regex Tester

Test regular expressions against text

Runs locally in your browser; input is never uploaded

Development & Debugging

Usage

Paste the subject text into the input and enter the pattern in the visible Regex option. Choose Match or Replace, a replacement value and g/i/m/s/u flags through controls. Run to copy a match summary or replaced text; an invalid pattern only produces diagnostics.

FAQ

1.
How do I set g, i, m, s and u flags?
Use the visible checkboxes. You do not need to put /pattern/flags on the first input line.
2.
Why does Replace mode replace every match?
Replace mode ensures global replacement. The replacement supports group-reference syntax from browser RegExp.replace.