AI solution for JavaScript Coding Question on BFE.dev
97. compress a string

Here's a possible solution for the coding question:

function compress(str) {
  let compressed = '';
  let count = 1;

  for (let i = 0; i < str.length; i++) {
    if (str[i] === str[i + 1]) {
      count++;
    } else {
      compressed += str[i];
      if (count > 1) {
        compressed += count;
        count = 1;
      }
    }
  }

  return compressed;
}

The function compress takes a string str as input and returns a compressed version of it as output. The compressed version replaces repeating consecutive letters with the letter followed by the count number of repetitions.

The implementation iterates through the string from left to right using a for loop, keeping track of the current count of consecutive letters. If the current letter is different from the next one, it means it's the end of a run, so the compressed string adds the letter and the count (if it's greater than 1). If the current letter is the same as the next one, the count is incremented to keep track of the consecutive letters.

As an example, if we call compress('aaabba'), the iteration will first encounter 'a', then 'a' again (which increases the count to 2), then 'a' again (which increases the count to 3), then 'b' (which adds 'a3b' to the compressed string), then 'b' again (which increases the count to 2), and finally 'a' (which adds 'a' to the compressed string). The function returns the compressed string 'a3b2a'.