À propos de Expression régulière
Match, capture, and replace text
A pattern is easier to trust when its test set includes expected matches, near-misses, Unicode, line breaks, and empty input. The tester is most useful as a small reproducible case for a regex that will later live in application code.
Comment utiliser cet outil développeur
- Enter the expression, flags, and representative test text.
- Review full matches and capture groups, then add cases that should not match.
- Try the replacement operation only after the match boundaries are correct, and keep the test examples with the expression.
Confidentialité et traitement des données
Regular-expression matching runs in the browser. Avoid pasting personal records or log files containing secrets; use short representative samples instead.
Outils développeur associés
Questions fréquentes
Why does a flag change the result?
Flags can change case sensitivity, line boundaries, Unicode behavior, or whether matching continues after the first result. Test them deliberately.
Can a regex validate an entire document?
It can check a pattern, but a regex is not always the right parser for nested or structured formats such as JSON, XML, or programming languages.
What is a near-miss test?
It is an input that looks close to a valid match but should be rejected. Near-misses reveal missing boundaries and overly broad quantifiers.