A very simplistic implementation of the binary search algorithm in javascript

binarySearch.js

// Simple Binary search implementation in Js

const binarySearch = (arr, key) => {
  if (arr == null || typeof arr === 'undefined') return null;
  
  if (arr.length === 1) {
    if (key === arr[0]) {
      return arr[0];
    } else {
      return 'not found';
    }
  }
  
  let i = Math.floor(arr.length / 2);
  
  for (let j = 0 ; j < i; j++) {
    if (key === arr[j]) {
      return arr[j];
    }
  }
  
  let newArrToSearch = arr.slice(i);
  
  return binarySearch(newArrToSearch, key);
}

const testBinarySearch = (arrayToSearch, key) => {
  const result = binarySearch(arrayToSearch, key);
  console.log(result);
}

testBinarySearch([1,2,310, 5, 23, 9], 1);
testBinarySearch(['dog', 'cat', 'some random text'], 'cat');