Matching Ranges for a certain value

areRangesMatching.js

const sample = [1, 6, 4, 10, 27, 15, 120, 25, 222, 30];
const sampl2 = [1, 6, 4, 10, 27, 15, 20, 25, 22, 30];

const isEven = integer => integer % 2 === 0;

const findValueFromAlternateSortedArray = (arr, search, prevIndex = 0) => {
  const arrLen = arr.length - 1;
  const pivotIndex = Math.floor(arrLen / 2);
  const nextPivotIndex = isEven(arrLen) ? pivotIndex : pivotIndex + 1;
  const pivotIndexValue = arr[pivotIndex];
  const nextPivotIndexValue = arr[nextPivotIndex];
  if (search === pivotIndexValue) {
    return pivotIndex;
  }
  if (search === nextPivotIndexValue) {
    return nextPivotIndex;
  }
  if (search < nextPivotIndexValue) {
    const leftHalf = arr.slice(0,pivotIndex);
    const index = findValueFromAlternateSortedArray(leftHalf, search);
    if (index !== -1) {
      return index;
    }
  }
  if (search > pivotIndexValue) {
    const rightHalf = arr.slice(nextPivotIndex);
    console.log(nextPivotIndex, prevIndex);
    const index = findValueFromAlternateSortedArray(rightHalf, search, nextPivotIndex + prevIndex);
    console.log(index);
    return index + prevIndex;
  }
  return -1;
}

console.log(findValueFromAlternateSortedArray(sampl2, 30));
// console.log(findValueFromAlternateSortedArray(sampl2, 1));
// console.log(findValueFromAlternateSortedArray(sampl2, 4));