🔍Regex Recipes

Detect Repeated Words

Find accidentally repeated words like "the the" in text.

Pattern

\b(\w+)\s+\1\b

Explanation

Captures a word and matches if it immediately repeats. Useful for proofreading.

Examples

Repeated word

Input

the the quick brown

Output

✓ Match: "the the"

Different case

Input

The the quick

Output

✓ Match (case-insensitive)

No repetition

Input

the quick brown

Output

✗ No match

Non-adjacent

Input

the quick the

Output

✗ No match

Code Examples

JavaScript

const text = 'I think think this is is a test';
const repeated = text.match(/\b(\w+)\s+\1\b/gi);
// Result: ['think think', 'is is']

// Find and highlight
function highlightRepeated(text) {
  return text.replace(
    /\b(\w+)\s+\1\b/gi,
    '<mark>$&</mark>'
  );
}

Try it Now

Open in Regex Tester

💡 Tips

Use case-insensitive flag (i) for better detection
Backreference \1 refers to first captured group
Consider word boundaries (\b) to avoid partial matches
Useful for automated proofreading

⚠️ Common Pitfalls

Case-sensitive by default (use i flag)
Only detects adjacent repetitions
Some repetitions are intentional
Does not detect similar words (their/there)