range.js

const isValidRange = (arr) => {
  let previous = null;
  const isLessThanPrevious = (curr) => {
    if (previous == null) {
      previous = curr;
      return true;
    }

    if (previous - 1 == curr) {
      previous = curr;
      return true;
    }

    return false;
  };

  return arr.every(isLessThanPrevious);
};

const calcRangeArrays = (scores) => {
  let total = 0;
  let range = 1;
  let leftPointer = 0;
  let rightPointer = 1;
  const scoresLength = scores.length;

  while (range <= scoresLength - 1) {
    for (let i = leftPointer; rightPointer < scoresLength; i++) {
      const arrRange = scores.slice(leftPointer, rightPointer + 1);
      if (isValidRange(arrRange)) total += 1;
      leftPointer += 1;
      rightPointer += 1;
    }
    range += 1;
    leftPointer = 0;
    rightPointer = range;
  }

  return total + scoresLength;
};

export default calcRangeArrays;