Text Processingflags: gi

Duplicate Word

Detects consecutive duplicate words using a backreference.

Try it in RegexPro →

Available in

JSSupported

JavaScript / ECMAScript

Browser-native RegExp. Default if you don't pick.

PYSupported

Python (re)

CPython stdlib `re`. Unicode-aware `\w` and `\d` by default.

GOSee workaround

Go (RE2)

Linear-time matching. No backreferences or lookarounds.

Pattern

regexengine-agnostic
\b(\w+)\s+\1\b   (flags: gi)

Raw source: \b(\w+)\s+\1\b

How it works

`\b(\w+)\b` captures a word. `\s+\1\b` matches whitespace followed by the same word (backreference `\1`). Case-insensitive.

Examples

Input

the the cat sat on the the mat

Matches

  • the the
  • the the

Input

no duplicates here

No match

—

Common use cases

  • •Proofreading
  • •Content editors
  • •Writing-quality linters

Related patterns

Word Boundary (Whole Word Match)

Text Processing

Match the whole word `cat` without matching it inside other words like `concatenate` or `category`.

Negative Lookahead

Text Processing

Use negative lookahead `(?!...)` to match words that are NOT in a blocklist (here: log-level keywords).

Single-Line Comment (// or #)

Text Processing

Match single-line comments using either the `//` (C-family) or `#` (shell, Python, Ruby, YAML) marker.

Base64 String

Text Processing

Match Base64-encoded strings, including proper padding with = and == characters.

Related concepts

Word Boundaries: \b and \B

Concept

\b matches the position between a word character and a non-word character. It keeps your regex from matching 'cat' inside 'concatenate.'

How to Replace Text Using Regex in JavaScript

How-to

String.replace and String.replaceAll accept a regex. Use the g flag for multi-match replace, $1/$2 for capture references, and a function for complex logic.

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