Given a positive integer n, find and return the longest distance between any two adjacent 1's in the binary representation of n. If there are no two adjacent 1's, return 0. Two 1's are adjacent if there are only 0's separating them (possibly no 0's)

binaryGap.js

/**
 * @param {number} n
 * @return {number}
 */
var binaryGap = function(n) {
    // Convert the number to its binary string representation.
    // Example: 22 -> "10110"
    const binary = n.toString(2);

    // This will store the index of the *previous* '1' we saw.
    // We start with null because we haven't seen any '1' yet.
    let prevOneIndex = null;

    // This will track the maximum distance found so far.
    let maxDistance = 0;

    // Loop through each character in the binary string.
    for (let i = 0; i < binary.length; i++) {
        // We're only interested in positions where the bit is '1'.
        if (binary[i] === '1') {

            // If we've seen a previous '1', compute the distance.
            if (prevOneIndex !== null) {
                const distance = i - prevOneIndex;

                // Update the maximum distance if this one is larger.
                maxDistance = Math.max(maxDistance, distance);
            }

            // Update prevOneIndex to the current index of '1'.
            prevOneIndex = i;
        }
    }

    // If there were fewer than two '1's, maxDistance will still be 0.
    return maxDistance;
};