How to Replace Two or More Consecutive Characters With a Single Character Using Regular Expressions?

Question

What is the regex pattern to replace two or more consecutive identical characters in a string with only one character?

/(.)\1+/g

Answer

Replacing consecutive characters in a string using regular expressions is a powerful technique often utilized in text processing. The regex pattern can be designed to identify duplicates and replace them with a single instance of the character, enhancing data consistency and readability.

const inputString = 'aaabbbcccd';
const outputString = inputString.replace(/(.)\1+/g, '$1');
console.log(outputString); // Output: 'abcd'

Causes

  • You may have mistakenly added multiple characters while typing.
  • Data entry errors could lead to multiple identical characters appearing in strings.

Solutions

  • Use a regex pattern that matches consecutive identical characters.
  • Apply a replacement function to substitute these duplicates with a single character.

Common Mistakes

Mistake: Using the wrong regex pattern that doesn't capture duplicates.

Solution: Ensure you use (.)\1+ to match consecutive identical characters.

Mistake: Forgetting to include the global flag 'g' which limits the replacement to the first occurrence only.

Solution: Always include 'g' at the end of your regex to ensure all instances are replaced.

Helpers

  • regular expressions
  • replace consecutive characters
  • regex pattern
  • string manipulation
  • JavaScript string replacement

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