Given an array in which elements at odd indices are sorted & elements at even indices are sorted individually. Please write a function to search an element in the array.

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

console.log(findValueFromAlternateSortedArray(sampl2, 30)); // 9
console.log(findValueFromAlternateSortedArray(sample, 25)); // 7
console.log(findValueFromAlternateSortedArray(sample, 30)); // 9 
console.log(findValueFromAlternateSortedArray(sampl2, 1)); // 0
console.log(findValueFromAlternateSortedArray(sampl2, 4)); // 2