Match 1 · index 8
17 charshello@example.com- Group 1
- hello
- Group 2
- example.com
Free JavaScript Regex Tester Online
Test a JavaScript regular expression against sample text. Inspect matches, indexes, capture groups, flags, and syntax errors before using the pattern in code.
Cost Free
Runtime Browser
Login Not required
JavaScript regex workspace
Test a pattern against sample text
Matches, indexes, and capture groups are calculated in this browser. This version does not emulate Python or PCRE.
Examples
Matches
2 matches · gi
Match 2 · index 29
16 charsteam@example.org- Group 1
- team
- Group 2
- example.org
Test a JavaScript Regular Expression
Step 1
Enter a pattern and test string
Paste a JavaScript pattern and the text you want to inspect, or load a safe example.
Step 2
Choose the flags
Toggle supported JavaScript flags such as global, case-insensitive, multiline, dotAll, and Unicode behavior.
Step 3
Review matches and capture groups
Check match text, indexes, groups, counts, and parser errors before copying the pattern into code.
Examples and common tasks
- Find email-like strings in a paragraph
- Test a URL or phone-number pattern
- Inspect a capture group before adding it to code
FAQ
Which regex flavor does this tester support?
The first version uses the browser's JavaScript RegExp engine. Python, PCRE, PHP, and other flavors can differ, so a pattern that works in one engine may not work here.
What do the g, i, and m flags mean?
g searches for multiple matches, i ignores letter case, and m changes how line anchors work. The tester only exposes flags supported by the JavaScript engine used in the page.
Can I see capture groups?
Yes. When a pattern contains capturing parentheses, the result lists the full match and the captured values for each match.
Why does my regular expression show an error?
The JavaScript parser rejects invalid syntax such as an unclosed character class, missing parenthesis, or unsupported flag. The error message appears beside the input.
Is my pattern or test text uploaded?
The tester evaluates the pattern and test string in this browser and does not require an account. Verify network behavior independently when working with sensitive text.
Can I use Python or PCRE syntax here?
Not as a separate engine in this first version. Use JavaScript-compatible syntax or test the pattern in the target language's own tool before shipping it.
Test a JavaScript Regular Expression
A focused workspace for checking whether a pattern matches the text you expect before you reuse it in code.
Enter a pattern and test string
The pattern and sample text remain separate so you can change either side without losing the other value.
Use common regex flags
Toggle the JavaScript flags supported by the workspace and rerun the same test to compare behavior.
Review matches and capture groups
Inspect full matches, indexes, and captured groups instead of relying only on a pass/fail label.
Understand Regex Results
A useful tester distinguishes a valid pattern with no matches from a pattern that the JavaScript parser cannot read.
No match versus invalid pattern
No match means the pattern parsed successfully but found nothing. An invalid-pattern message means the JavaScript RegExp constructor rejected the syntax.
JavaScript flavor boundaries
Regex engines differ in flags, escapes, lookbehind, named groups, and replacement syntax. Test in the engine that will run your code.
Long input and complex patterns
Large text and pathological patterns can consume browser time. Keep examples practical and stop processing if the page becomes unresponsive.
Common Regex Tasks
Use small examples to validate the workflow, then adapt the pattern to your own data and test cases.
Email and URL examples
Examples are useful starting points, not complete validation guarantees for every email address or URL standard.
Capture groups and extraction
Use parentheses when you need a specific part of a match, then confirm the group values in the result table.
Copy and reuse a tested pattern
Copy the pattern or test text only after checking flags and the target language's regex flavor.
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