AI solution for JavaScript Coding Question on BFE.dev
138. Intersection of two sorted arrays

One possible solution in JavaScript:

function intersect(arr1, arr2) {
  let i = 0; 
  let j = 0;
  let result = [];
  while (i < arr1.length && j < arr2.length) {
    if (arr1[i] === arr2[j]) {
      result.push(arr1[i]);
      i++;
      j++;
    } else if (arr1[i] < arr2[j]) {
      i++;
    } else {
      j++;
    }
  }
  return result;
}

The time complexity of this approach is O(m + n), where m and n are the lengths of the two arrays. This is because we need to compare each element of both arrays exactly once in the worst case. The space complexity is O(min(m, n)), since we only need to store the common elements, which cannot exceed the length of the shorter array.

This solution assumes that the input arrays are already sorted. If they are not sorted, we can sort them first using a sorting algorithm such as merge sort, which has a time complexity of O(n log n).

We could also optimize the solution by using a hash table to keep track of the elements in one of the arrays, and then checking the other array for matches. This would have a time complexity of O(m + n) and a space complexity of O(min(m, n)), but would take more time to build the hash table initially.