get the last item of array set map object js

1row.map((rank, i, arr) => {
2    if (arr.length - 1 === i) {
3        // last one
4    } else {
5        // not last one
6    }
7});
8

1const lastItem = (list) => {
2  if (Array.isArray(list)) {
3    return list.slice(-1)[0];
4  }
5
6  if (list instanceof Set) {
7    return Array.from(list).slice(-1)[0];
8  }
9
10  if (list instanceof Map) {
11    return Array.from(list.values()).slice(-1)[0];
12  }
13
14  if (!Array.isArray(list) && typeof list === "object") {
15    return Object.values(list).slice(-1)[0];
16  }
17
18  throw Error(`argument "list" must be of type Array, Set, Map or object`);
19};
20
21// Usage
22const l1 = lastItem(["a", "b", "c"]);
23// c
24
25const l2 = lastItem(new Set(["d", "e", "f"]));
26// f
27
28const l3 = lastItem(
29  new Map([
30    ["a", "x"],
31    ["b", "y"],
32    ["c", "z"]
33  ])
34);
35// z
36
37const l4 = lastItem({ a: "x", b: "y", c: "z" });
38// z