Regex Tester

What is Regex Tester?

A regex tester runs your pattern against sample text as you type, highlighting each match and listing the position and content of every capture group, with support for the g, i, m, s, and u flags. Matching uses the browser native regular expression engine, so your test text is never uploaded.

How to use Regex Tester

1. 1Enter your regular expression — you do not need the surrounding slashes.
2. 2Tick the flags you need; check g for global matching.
3. 3Paste sample content into the test text box and matches highlight instantly.
4. 4Check the group list underneath to confirm the captured text and indexes are what you expect.

How do I do this in code?

Use the tool above for one-off work; for anything you repeat, move it into a script or your project.

const re = /(\d{4})-(\d{2})-(\d{2})/g;

for (const m of text.matchAll(re)) {
  console.log(m[0], m[1], m[2], m[3], m.index);
}

Common errors and how to fix them

Frequently asked questions