Regex

Regex Flag Tester

Compare a JavaScript regex independently with no flags and each of g, i, m, s, u, y and d, including browser support errors.

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Flag comparisons

Your result will appear here.

Rows compare No flags, g, i, m, s, u, y and d independently, never cumulatively. Unsupported flags or invalid patterns are reported on their own row.

Uses your browser’s JavaScript RegExp engine. Positions and lengths are zero-based UTF-16 code units; end positions are exclusive. Without g, matching returns only the first match. Sticky y starts at position 0.

Limits: 16,384 pattern code units, 200,000 text code units, 2,000 matches or split parts, and 4,000,000 output code units. User regex execution requires a local worker with a 1,500 ms timeout. Oversized results fail rather than being truncated.

Processed locally in your browser. Inputs and results are not uploaded or saved by this page.

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What does this tool do?

Compare a JavaScript regex independently with no flags and each of g, i, m, s, u, y and d, including browser support errors. Code Station Regex tools use the JavaScript regular expression engine. Inputs: Regex Pattern, Test text. Outputs: Flag comparisons.

How to use it?

Enter one JavaScript pattern and test text. Each of the eight rows runs independently with its named flag only. Choose “Compare flags”, then copy individual result values if needed. Clear removes all inputs and results and restores option defaults.