get / set properties using dot notation

objectUtils.ts

// property can have dot notation, eg 'parent.child.value'
export const getPropertyValue = (obj: any, property: string) =>
  property.split('.').reduce((a, b) => (a ? a[b] : undefined), obj);

// property can have dot notation, eg 'parent.child.value'
export const setPropertyValue = (obj: any, property: string, value: any) => {
  const keys = property.split('.');
  const lastKey = keys.pop()!;
  let currentObj = obj;
  keys.forEach((key) => {
    if (currentObj[key] == null) {
      currentObj[key] = {};
    }
    currentObj = currentObj[key];
  });
  currentObj[lastKey] = value;
};


// objectUtils.test.ts
// import { getPropertyValue, setPropertyValue } from './objectUtils';

describe('object utils: getPropertyValue', () => {
  const obj = {
    parent: {
      child: {
        value: 42,
      },
    },
  };

  it('returns parent object', () => {
    const parent = getPropertyValue(obj, 'parent');
    expect(parent).toStrictEqual({ child: { value: 42 } });
  });

  it('returns child object', () => {
    const child = getPropertyValue(obj, 'parent.child');
    expect(child).toStrictEqual({ value: 42 });
  });

  it('returns child.value', () => {
    const value = getPropertyValue(obj, 'parent.child.value');
    expect(value).toBe(42);
  });

  it('when property is undefined returns undefined', () => {
    const value = getPropertyValue(obj, 'foo.bar');
    expect(value).toBeUndefined();
  });
});

describe('object utils: setPropertyValue', () => {
  const obj = {
    parent: {
      child: {
        value: 42,
      },
    },
  };

  it('sets child value', () => {
    setPropertyValue(obj, 'parent.child.value', 9000);
    expect(obj.parent.child.value).toBe(9000);
  });

  it('sets new child value', () => {
    setPropertyValue(obj, 'parent.child.foo', 9000);
    expect((obj as any).parent.child.foo).toBe(9000);
  });

  it('sets value on undefined', () => {
    setPropertyValue(obj, 'foo.bar', 9000);
    expect((obj as any).foo.bar).toBe(9000);
  });
});