Regex Tester
Inspect JavaScript matches, capture groups and start indices before using a pattern in code.
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Regular expressions
Test JavaScript patterns, interpret matches and handle failure cases.
Start with a task
Understand the workflow
Regular expressions
JavaScript regex flags explained through observable examples
Choose regex flags deliberately.
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Regular expressions
Regex anchors and word boundaries: search vs full validation
Prevent partial regex matches.
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Regular expressions
Capture groups, named groups and non-capturing groups
Extract structured fields using regex.
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Regular expressions
Recognize regex backtracking problems before they freeze a page
Diagnose slow regular expressions.
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Regular expressions
Unicode regex matches and JavaScript UTF-16 indices
Interpret regex offsets in Unicode text.
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Regular expressions
Extract fields from simple logs without building a fragile parser
Extract diagnostic fields from log lines.
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Regular expressions
What regex validation can—and cannot—prove
Choose validation layers appropriately.
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