intersection.js

var intersect = function(nums1, nums2) {
    let fn = (a, b) => a - b;

    nums1.sort(fn);
    nums2.sort(fn);

    let res = [];
    let i = 0;
    let j = 0;

    while (i < nums1.length && j < nums2.length) {        
        if (nums1[i] === nums2[j]) {
            res.push(nums1[i]);
            i++;
            j++;
        } else if (nums1[i] < nums2[j]) {
            i++;
        } else {
            j++;
        }
    }

    return res;
};