Vintage Binary Search

vintage-binary-search.js

// binary search need a pre-sorted array
const binarySearch = (items, itemToFind, start, end) => {

  // Base Condition
  if (start > end) return null;

  // Find the middle index
  const mid = Math.floor((start + end) / 2);

  // Compare mid with given key itemToFind
  if (items[mid] === itemToFind) return mid;

  // If element at mid is greater than itemToFind,
  // search in the left half of mid
  if (items[mid] > itemToFind)
    return binarySearch(items, itemToFind, start, mid - 1);
  else
    // If element at mid is smaller than itemToFind,
    // search in the right half of mid
    return binarySearch(items, itemToFind, mid + 1, end);
};

const tab = [10, 11, 12, 13, 14, 15, 16];
const start = 0;
const end = tab.length - 1;
const elementToFind =  11;
const elementIndex = binarySearch(tab, elementToFind, start, end);
console.log('element index : ', elementIndex);