binary search

function binarySearch (search, arr) {
    let lower = 0;
    let upper = arr.length;

    while (lower < upper) {
        let mid = lower + Math.floor((upper - lower) / 2);

        if (arr[mid] === search) {
            return mid;
        } else if (arr[mid] < search) {
            lower = mid + 1;
        } else {
            upper = mid; 
        }
    }

    return -1;
}


const test = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];


for (let i=0; i<=test.length; i++) {
    let foundIndex = binarySearch(i, test);
    console.log(`test ${i} :: ${foundIndex}`);
}