Daily JavaScript Challenge #JS-185: Find First Repeated Character in a String

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Daily JavaScript Challenge: Find First Repeated Character in a String

Hey fellow developers! 👋 Welcome to today's JavaScript coding challenge. Let's keep those programming skills sharp!

The Challenge

Difficulty: Easy

Topic: String Manipulation

Description

Write a function that finds the first character in a given string that repeats compared to the characters that precede it. If there is no such character, return 'None'.

Ready to Begin?

https://www.dpcdev.com/

Fork this challenge
Write your solution
Test it against the provided test cases
Share your approach in the comments below!

Want to Learn More?

Check out the documentation about this topic here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Set

Join the Discussion!

How did you approach this problem?
Did you find any interesting edge cases?
What was your biggest learning from this challenge?

Let's learn together! Drop your thoughts and questions in the comments below. 👇

This is part of our Daily JavaScript Challenge series. Follow me for daily programming challenges and let's grow together! 🚀

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Top comments (2)

Sean Dinan • May 27

I'm sure it could be better optimized, but I just took a simple iteration approach:

function firstRepeatedCharacter(str) {
  const split = str.split('');
  for (let i = 0; i < split.length; i++){
      const index = split.findIndex(char => char === split[i]);
      if (index !== undefined && index !== i){
          return split[i];
      }
  }
  return 'None';
}

Dotallio • May 27

I always get tripped up by strings where no character repeats at all, like 'abc', so I make sure to test that early. Did anyone find a one-liner approach they liked?

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