DAY5 - Binary Search - Find first number 1 in array

findFirstOne.js

function findFirstOne(arr) {
    let L = 0;
    let R = arr.length - 1;
    let result = -1;
    while (L <= R) {
        let mid = Math.floor(L + (R - L) / 2);
        if (arr[mid] === 1) {
            result = mid;
            R = mid - 1;
        } else {
            L = mid + 1;   
        }
    }
    return result;
}