function binarySearch(arr, val) {
let start = 0;
let end = arr.length - 1;
while (start <= end) {
let mid = Math.floor((start + end) / 2);
if (arr[mid] === val) {
return mid;
}
if (val < arr[mid]) {
end = mid - 1;
} else {
start = mid + 1;
}
}
return -1;
}
// JavaScript program to implement recursive Binary Search
// A recursive binary search function. It returns
// location of x in given array arr[l..r] is present,
// otherwise -1
function binarySearch(arr, l, r, x){
if (r >= l) {
let mid = l + Math.floor((r - l) / 2);
// If the element is present at the middle
// itself
if (arr[mid] == x)
return mid;
// If element is smaller than mid, then
// it can only be present in left subarray
if (arr[mid] > x)
return binarySearch(arr, l, mid - 1, x);
// Else the element can only be present
// in right subarray
return binarySearch(arr, mid + 1, r, x);
}
// We reach here when element is not
// present in array
return -1;
}
let arr = [ 2, 3, 4, 10, 40 ];
let x = 10;
let n = arr.length
let result = binarySearch(arr, 0, n - 1, x);
(result == -1) ? document.write( "Element is not present in array") : document.write("Element is present at index " +result);
const arr = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30];
const binarySearch = (arr, x , start=0, end=arr.length) => {
if(end < start) return -1;
let mid = Math.floor((start + end) / 2);
if(arr[mid] === x) return mid;
if(arr[mid] < x) return binarySearch(arr, x, mid+1, end);
else return binarySearch(arr, x , start, mid-1);
}
console.log(arr[binarySearch(arr,8)]);