Regex Replace Tester

Apply a regex pattern and replacement value to see the result.

Category: Dev Tools

When to use?

Use it to test a regex replacement rule for text normalization or data transformation before applying it for real.

How to use

  • Enter the regex pattern.
  • Enter the replacement value ($1, $2 capture groups allowed).
  • Enter test text to see the replaced result.

Input Explanation

Enter the search regex, the replacement string, and the target text.

Calculation Basis

It uses JavaScript String.replace() to replace all substrings matching the regex with the replacement (including $1, $2 backreferences) in real time.

Usage Examples

  • Normalize text - Preview results before applying a regex replacement rule.
  • Quick pre-deploy check - Check inputs and output to reduce errors before dev/ops work.
  • Aid docs/reviews - Copy the result into dev docs, issues, or review comments.

Examples

  • Pattern (\d{4})-(\d{2})-(\d{2}), replace $3/$2/$1 → "2025-05-12" → "12/05/2025"
  • Bulk-replace date formats across multi-line logs

Cautions

  • Generated output is for reference; test carefully before production use.
  • Regex follows the JavaScript engine, which can differ from other languages.

Guides

How regex replace works

Enter a search pattern (regex) and replacement text to preview the result with all matches replaced. Use capture groups like $1, $2 in the replacement string.

Mind the global flag

Without the g flag, only the first match is replaced. Include the g flag when you need to replace all occurrences.

FAQ

Can I use capture groups?

Yes, JavaScript replace syntax like $1, $2 is supported.

Do results update live?

Yes. Editing the pattern or replacement recalculates instantly.

Can I use flags like ignore-case?

Apply flags like g, i, m to test global or case-insensitive replacement.

Does it replace all matches at once?

With the g flag it replaces all matches; without it, only the first.

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