merge Objects Recursively

mergeObjectsRecursively.ts

import isEqual from 'lodash.isequal';

type AnyObj = Record<string, any>;
type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends (k: infer I) => void
  ? I
  : never;

export const mergeObjectsRecursively = <T extends AnyObj, U extends AnyObj[]>(
  ...objects: [T, ...U]
): T & UnionToIntersection<U[number]> => {
  const result = {} as T & UnionToIntersection<U[number]>;

  objects.forEach((obj) => {
    Object.entries(obj).forEach(([key, value]) => {
      if (Array.isArray(value) && Array.isArray(result[key])) {
        const uniqueElements = value.filter(
          (element) => !result[key].some((item: any) => isEqual(item, element))
        );
        (result[key] as any) = [...result[key], ...uniqueElements];
      } else if (
        typeof value === 'object' &&
        value !== null &&
        typeof result[key] === 'object' &&
        result[key] !== null
      ) {
        (result[key] as AnyObj) = mergeObjectsRecursively(result[key], value);
      } else {
        (result[key] as any) = value;
      }
    });
  });

  return result;
};


const obj1 = {
  imya: 'John',
  age: 30,
  foo: {
    bar: 'bащщщщщaz',
  },
  arr: [1, 2, 3],
  action: {
    first111: () => console.log('111', 111)
  },
  hobbies: ['coding', 'reading', 'swimming', { foo: 'bar' }],
};
const obj2 = {
  age: 31,
  cool: false,
  foo: {
    bar: 'baz',
    baz: 'bar',
  },
  arr: [3, 4],
  hobbies: ['coding', 'hiking', { foo: 'bar' }],
};
const obj3 = {
  cool: true,
  action: {
    first111: () => console.log('1', 1),
    first222: () => console.log('222', 222)
  },
};

const mergedObj = mergeObjectsRecursively(obj1, obj2, obj3);

console.log('>>> mergedObj', mergedObj);