timsort.js

const possibleBalance = (program, targetValue) => {
  program = program.split('');

  for (let i = program.length; i > 0; i--) {
    let currentSum = 0;

    currentSum = sum(program.slice(0, i));
    
    if (currentSum >= targetValue) {
      return program.length - i;
    }
  }

  return -1;
}

const sum = (prog) => {
  let count = 0;

  prog.forEach(char => {
    if (char === '+') {
      count += 1;
    } else if (char === '-') {
      count -= 1;
    } else {
      console.log('error!');
    }
  })

  return count;
}

// test cases
console.log(possibleBalance("+++-++-++--+-++++-+--++-++-+-++++-+++--", 12) == 1);
console.log(possibleBalance("+++-++-++--+-++++-+--++-++-+-++++-+++--", 13) == 2);
console.log(possibleBalance("+++-++-++--+-++++-+--++-++-+-++++-+++--", 14) == -1);
console.log(possibleBalance("+++---", 3) == 3);
console.log(possibleBalance("+++-+---", 3) == 3);
console.log(possibleBalance("----+-", -2) == 4);