/* In this We will learn how to search for an item in Sorted array using Binary Search .*/

function binarySearch( item , arr ) {
    let first = 0;    //left endpoint or index of first array element 
    let last = arr.length - 1;   //right endpoint or index of lat array element .
 
    while (first <= last) {
        let middle = Math.floor((first + last)/2);
        if ( arr[middle] == item ) { 
          // If the element is present at the middle itself
          return middle ; 
         
        }
        else if ( arr[middle] > item ) {  
            // Ignore Right Half i.e. items after middle element .
            last = middle - 1;
        } 
        else { 
            // Ignore Right Half i.e. items after middle element .
            first = middle + 1;
        }
    }
    return -1;     //Item is not present in Array .
}

console.log(binarySearch(6,[2, 6, 8]));         //expected output = 1
console.log(binarySearch(10,[2, 3, 10, 14]));   //expected output = 2
console.log(binarySearch(1,[2, 6, 8]));         //expected output = -1