Regex Tester

[
  {
    "index": 1,
    "length": 1,
    "value": "1",
    "groups": []
  },
  {
    "index": 3,
    "length": 2,
    "value": "22",
    "groups": []
  },
  {
    "index": 6,
    "length": 3,
    "value": "333",
    "groups": []
  }
]

Found 3 match(es) for /\d+/g.

How it works

• Compiled a fresh regular expression from the pattern and flags.
• Advanced through the subject collecting every global match.
• Recorded each match's start index, length, value, and capture groups.

• A fresh RegExp is compiled on every call, so lastIndex never leaks between tests.

Usage

1. Enter a regular expression pattern.
2. Optionally add flags such as g, i, or m.
3. Paste the subject text and read the matches and groups.

Examples

All digits

{
  "pattern": "\\d+",
  "flags": "g",
  "subject": "a1b22c333"
}

Capture groups

{
  "pattern": "(\\w+)@(\\w+)\\.com",
  "subject": "[email protected]"
}

Limitations

Global state and lastIndex

A RegExp with the g or y flag stores its position in lastIndex. Reusing one object between tests is a classic source of 'every other match is skipped' bugs. This tool compiles a new RegExp for each call, so results are reproducible.