binarySearch

function binarySearch(arr, n){
    var low = 0, high = arr.length-1, mid = Math.floor((low+high)/2);
    while( low<=high ){
        if( arr[mid]==n )
            return mid;
        else if( arr[mid]>n ){
            high = mid-1;
            mid = Math.floor((low+high)/2);
        }
        else if( arr[mid]<n ){
            low= mid+1;
            mid = Math.floor((low+high)/2);
        }
    }
    return -1;
}