merge

This function recursively merges two objects and accepts a composer function to modify values based on a path or key.For array, map, and set, it concatenates values together, other values are overwritten by the second object.

Import


import { merge } from '@fullstacksjs/toolbox';

Signature


function merge<T extends ObjectType, U extends ObjectType>(
  obj1: T,
  obj2: U,
  composer: Composer,
): unknown;
function merge<T extends ObjectType, U extends ObjectType>(
  obj1: T,
  obj2: U,
): Merge<T, U>;
function merge<T extends ObjectType, U extends ObjectType>(
  obj1: T,
  obj2: U,
  composer: Composer = defaultComposer,
): Merge<T, U>;

Examples


const obj1 = {
  a: 1,
  b: {
    c: [1, 2, 3],
    b: {
      b: {
        foo: false,
      },
    },
  },
};
 
const obj2 = {
  b: {
    c: [4, 5, 6],
    d: 'bar',
    b: {
      b: {
        bar: [true, 1, 2, 3],
      },
    },
  },
  f: 2,
};
 
const merged = merge(obj1, obj2);
// { a: 1, b: { c: [ 1, 2, 3, 4, 5, 6 ], b: { b: { foo: false, bar: [ true, 1, 2, 3 ] } }, d: 'bar' }, f: 2 }
 
const mergedWithComposer = merge(obj1, obj2, args => {
  if (args.path === 'obj.b.b.b') return 'foo';
 
  return merge.defaultComposer(args);
});
// { a: 1, b: { c: [ 1, 2, 3, 4, 5, 6 ], b: { b: 'foo' }, d: 'bar' }, f: 2 };