reactive readonly嵌套对象转换功能实现详解

// src/reactivity/tests/reactive.spec.ts
it('nested reactive', () => {
  const original = {
    nested: { foo: 1 },
    array: [{ bar: 2 }]
  };
  const observed = reactive(original);
  expect(isReactive(observed.nested)).toBe(true);
  expect(isReactive(observed.array)).toBe(true);
  expect(isReactive(observed.array[0])).toBe(true);
});

it('nested readonly', () => {
  const original = { foo: 1, bar: { baz: 2 } };
  const wrapped = readonly(original);
  expect(isReadonly(wrapped)).toBe(true);
  expect(isReadonly(wrapped.bar)).toBe(true);
});

function createGetter(isReadonly = false) {
  return function get(target, key) {
    const res = Reflect.get(target, key);
    if (key === ReactiveFlags.IS_REACTIVE) {
      return !isReadonly;
    } else if (key === ReactiveFlags.IS_READONLY) {
      return isReadonly;
    }
    if (isObject(res)) {
      return isReadonly ? readonly(res) : reactive(res);
    }
    if (!isReadonly) {
      track(target, key);
    }
    return res;
  };
}