SMS sender

solution.js

const solution = (S, K) => {
  const words = S.split(' ');
  if (words.some(word => word.length > K)) return -1;
  let counter = 0;
  while (words.length > 0) {
    const firstWord = words.shift();
    let freeSpace = K - firstWord.length - 1;
    if (words.length === 0 || freeSpace <= 0) {
      counter++;
    }
    while (freeSpace > 0 && words.length > 0) {
      if (words[0].length > freeSpace && words[0]) {
        counter++;
        freeSpace = -1;
      } else {
        const justOne = words.shift();
        freeSpace = freeSpace - justOne.length - 1;
        if (freeSpace <= 0 || words.length === 0) {
          counter++;
        }
      }
    }
  }
  return counter;
};