Given a binary array nums, you should delete one element from it. Return the size of the longest non-empty subarray containing only 1's in the resulting array. Return 0 if there is no such subarray.

longestSubarray.js

/**
 * Finds the length of the longest subarray containing only 1s
 * after deleting exactly one element (which can be a 0).
 *
 * @param {number[]} nums - Array of binary digits (0s and 1s)
 * @return {number} - Length of the longest valid subarray
 */
var longestSubarray = function(nums) {
    let maxLength = 0;      // Tracks the maximum length found
    let left = 0;           // Left pointer of the sliding window
    let zeroCount = 0;      // Number of zeros in the current window

    for (let right = 0; right < nums.length; right++) {
        // Expand the window by including nums[right]
        if (nums[right] === 0) {
            zeroCount++;
        }

        // Shrink the window if more than one zero is present
        while (zeroCount > 1) {
            if (nums[left] === 0) {
                zeroCount--;
            }
            left++; // Move the left pointer forward
        }

        // Update maxLength (we subtract 1 to simulate deleting one element)
        maxLength = Math.max(maxLength, right - left + 1);
    }

    // Subtract 1 to account for the required deletion
    return maxLength - 1;
};