stringCompression.js

/*
  Write a function `compression` which takes a string as input and returns a compressed version of the string. The compression is done by replacing consecutive repeating characters with the character followed by the count of repetitions. If a character does not repeat, it is not followed by a count.

  Example:
  - Input: "aaabbbbcccvvmm"
  - Output: "a3b4c3v2m2"

  - Input: "abc"
  - Output: "abc"

  - Input: "aabbcc"
  - Output: "a2b2c2"

  - Input: ""
  - Output: ""

  Note:
  - The function should work for any alphanumeric string.

  Once you've implemented the logic, test your code by running
  - `npm run test-compressString`
*/

function compression(s){
  let n=s.length;
  let cnt=0;
  let ans="";

  for(let i=0; i<n; i++){
    cnt++;
    if(s[i]!==s[i+1]){
      ans+=s[i];
      if(cnt>1){
        ans+=cnt;
      }
      cnt=0;
    }
  }

  return ans;
}

module.exports = compression;