Binary Search Example in JS -

 

Solution :

function binarySearch(arr, val, start, end){

    let mid  =  Math.floor((end - start) / 2);

    if(arr[mid] === val){

        return mid;

    }

    if(arr[mid] > val){

        start = start;

        end = mid    

        return binarySearch(arr, val, start, end);

    }

    if(arr[mid] < val){

        start = mid;

        end = mid    

        return binarySearch(arr, val, start, end);

    }

}

var arr = [72, 3, 6, 8, 9, 25, 4, 18];

//first sorting the given array

arr..sort(function (a, b) {  return a - b;  });    OR   arr.sort((a, b) => a-b);

[3, 4, 6, 8, 9, 18, 25, 72]

var res = binarySearch(arr, 6, 0, arr.length);

console.log(res);

Output:  2