index.ts

// create a binary search function that takes in a non-sorted array and a target value
const binarySearch = (arr: number[], target: number) => {
  // sort the array
  arr.sort((a, b) => a - b);

  // create a left and right pointer
  let left = 0;
  let right = arr.length - 1;

  // loop while left is less than or equal to right
  while (left <= right) {
    // create a middle pointer
    const middle = Math.floor((left + right) / 2);

    // if the target is at the middle, return the middle
    if (arr[middle] === target) return middle;

    // if the target is greater than the middle, move the left pointer up
    if (arr[middle] < target) left = middle + 1;

    // if the target is less than the middle, move the right pointer down
    if (arr[middle] > target) right = middle - 1;
  }

  // if the target doesn't exist in the array, return -1
  return -1;
};