O que Regex Tester faz?
Regex Tester permite inspecionar dados diretamente no navegador e informa com clareza o resultado e os limites. Recursos verificados: JavaScript RegExp engine, Capture groups, 300 ms worker timeout, 1,000-match cap.
Test against the deployment engine
Use this page for JavaScript patterns. Verify a PCRE, Python, .NET, Java, database, or proxy pattern in that exact engine before deployment.
Como usar?
- Enter the pattern without surrounding slash characters.
- Choose JavaScript flags and paste representative test text.
- Inspect highlighted matches, indexes, and capture groups.
Exemplo real de entrada e saída
Capture a named numeric identifier
Entrada
Pattern: order-(?<id>\d+)
Text: order-1042Saída
Match: order-1042
Named group id: 1042The browser exposes the full match and the named capture from the JavaScript RegExp result.
Erros comuns e correções
| Sintoma | Causa provável | Correção |
|---|---|---|
| A valid-looking pattern is rejected. | It uses syntax from another regex engine or an unsupported browser flag. | Rewrite the expression for the target JavaScript runtime. |
| Testing times out. | The expression backtracks heavily on the supplied text. | Make repetitions more specific, reduce ambiguity, or use a parser. |
A timeout indicates expensive matching
Limite específico desta ferramenta: Nested quantifiers and ambiguous repeated groups can cause excessive backtracking. A 300 ms timeout protects the page but does not certify production safety.
Padrões e referências de implementação
- MDN — RegExp (opens in a new tab)Documents JavaScript pattern syntax, flags, and match behavior.
Regex Tester — FAQ
Which regex engine is used?
The page uses JavaScript RegExp; PCRE, Python, .NET, and Java can behave differently.
Are capture groups shown?
Yes. Numbered captures and named groups are shown for displayed matches.
What does the timeout mean?
The worker is stopped after 300 ms to reduce page freezes; this is not proof that a pattern is safe.
O que mudou?
Atualização material: Regex Tester: Added JavaScript flag validation, highlighted matches, capture groups, a 1,000-match cap, and 300 ms worker termination for slow patterns.