const myArray = [1, 3, 7, 9, 10, 20];

function binarySearch(arr, value) {
	let first = 0;
  let last = arr.length - 1;
  let middle = Math.floor((first + last) / 2);

  if (arr[middle] > value) {
  	const newArr = arr.slice(0, middle);
    return binarySearch(newArr, value);
  } else if (arr[middle] < value) {
  	const newArr = arr.slice(middle + 1, arr.length);
    return binarySearch(newArr, value);
  } else {
  	return true;
  }
}

const anum = binarySearch(myArray, 10);

console.log(anum)