What Is a Regular Expression?
A regular expression describes a text pattern. JavaScript can use a pattern to find or check parts of a string.
How to Test a Regex
Enter the pattern and sample text in the tool. Review the matches and change flags as needed. Correct invalid expressions before relying on the results.
Regex Example
- \d+ with order 42 → Matches the digits 42 in the sample text.
Practical Uses
- Explore a pattern for extracting identifiers from a sample.
- Check how case sensitivity affects matches.
- Experiment with multiline text before using a pattern in code.
Frequently Asked Questions
Do regex flavors differ?
Yes. This tester uses JavaScript regular expressions; another language or engine may behave differently.
What does the global flag do?
It allows the expression to find multiple matches rather than only the first.