Daily JavaScript Challenge #JS-84: Find the First Repeated Character in a String

Daily JavaScript Challenge: Find the 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

Given a string, find and return the first character that repeats. If there is no such character, return null.

Ready to Begin?

https://www.dpcdev.com/

1. Fork this challenge
2. Write your solution
3. Test it against the provided test cases
4. 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. 👇

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Comments

[Peter Vivo]

"owqiqroiqwhfuiffeuuuueqwyuyewquy"
  .split('')
  .find(
    (c,i,list) => c === list[i+1]
  )
;

/** @type {(str:string) => string | undefined} */
const firstRepeat = str => str
  .split('')
  .find(
   (chr ,idx , list) => chr === list[idx + 1]
  )
;

[ThatGuyJK🕵🏾‍]

Your code for the first snippet returns 'f' when it should return 'q'

[Peter Vivo]

"feqnjoiwqejjif".split('').find((c,i,arr) => arr.indexOf(c)<i)

/** @type {(str:string) => string | undefined} */
const firstRepeat = str => str
  .split('')
  .find(
   (chr ,idx , list) => list.indexOf(chr) < idx)
  )
;

[Peter Vivo]

you right, may I misunerstund the request and write a first repeated char not second occurance.

[Krystian Ogonowski]

The login page has poor UX btw, the form doesn't show any errors if they are made.