set

1/**
2 * Sets a nested value in an object using a dot-separated path.
3 * Creates nested objects as needed.
4 *
5 * @param obj - The target object to modify.
6 * @param path - The dot-separated path string (e.g. "a.b.c").
7 * @param value - The value to set at the given path.
8 */
9export function set(obj: any, path: string, value: any): void {
10  if (typeof path !== 'string' || !path.length) return;
11
12  const keys = path.split('.');
13  let current = obj;
14
15  for (let i = 0; i < keys.length - 1; i++) {
16    const key = keys[i];
17    if (
18      current[key] === undefined ||
19      typeof current[key] !== 'object' ||
20      current[key] === null
21    ) {
22      current[key] = {};
23    }
24    current = current[key];
25  }
26
27  current[keys[keys.length - 1]] = value;
28}

1test('set - sets a deeply nested value', () => {
2  const obj = {};
3  set(obj, 'a.b.c', 42);
4  expect(obj).toEqual({ a: { b: { c: 42 } } });
5});
6
7test('set - overrides existing value', () => {
8  const obj = { a: { b: { c: 10 } } };
9  set(obj, 'a.b.c', 99);
10  expect(obj.a.b.c).toBe(99);
11});
12
13test('set - creates missing intermediate objects', () => {
14  const obj = {};
15  set(obj, 'x.y.z', 'value');
16  expect(obj).toEqual({ x: { y: { z: 'value' } } });
17});
18
19test('set - handles single-level path', () => {
20  const obj = {};
21  set(obj, 'key', 123);
22  expect(obj.key).toBe(123);
23});
24
25test('set - does nothing for empty path', () => {
26  const obj = { a: 1 };
27  set(obj, '', 'ignored');
28  expect(obj).toEqual({ a: 1 });
29});
30
31test('set - overwrites non-object intermediate values', () => {
32  const obj = { a: null };
33  set(obj, 'a.b', 5);
34  expect(obj).toEqual({ a: { b: 5 } });
35});