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Consecutive characters count in String

Consecutive characters count in String with JavaScript

Print the given string with the consecutive characters count next to each character, for example, Input: “aabccca” then Expected Output: “a2b1c3a1”. I tried a couple of things and decided to go with a simple for loop as this gives us access to the index with a single iteration, i.e., Linear time complexity O(n).

Code to Count Consecutive characters

// JavaScript code to print Consecutive characters of a String

const getCount = (inputString = "") => {
  let outputString = "";
  let characterCount = 1;

  for (let i = 0; i < inputString.length; i++) {
    const character = string[i];
    const nextCharacter = string[i + 1];

    if (character === nextCharacter) {
    } else {
      outputString += `${character}${characterCount}`;
      characterCount = 1;

  return outputString;

const string = "aabcca";
// Output: a2b1c2a1


The code is simple and straightforward but I am curious if there are more ways to do the same. One of my previous posts could be an interesting read as I have solved the same problem in four different methods – Count Vowels in a String with JavaScript.