recursive_binary_search.js

let recursiveFunction = function (arr, x, start, end) {

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

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

	// Compare mid with given key x
	if (arr[mid] === x) return arr[mid];

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

}

// Driver code
let arr = [1, 3, 6, 13, 17, 89, 99, 102, 131, 234, 654, 888, 990, 1001, 1502, 1901];
let x = 1001;

if (recursiveFunction(arr, x, 0, arr.length - 1))
	console.log("Element found!<br>", recursiveFunction(arr, x, 0, arr.length - 1));
else console.log("Element not found!<br>");

x = 6;

if (recursiveFunction(arr, x, 0, arr.length - 1))
	console.log("Element found!<br>", recursiveFunction(arr, x, 0, arr.length - 1));
else console.log("Element not found!<br>");