merge-deep

Deep merging of objects

This feature allows you to deeply merge multiple objects into one. It recursively merges own and inherited enumerable properties of source objects into the destination object, skipping source properties that resolve to `undefined`.

{"const mergeDeep = require('merge-deep');\nconst object1 = { a: { b: 1 } };\nconst object2 = { a: { c: 2 }, d: 3 };\nconst result = mergeDeep(object1, object2);\nconsole.log(result); // Output: { a: { b: 1, c: 2 }, d: 3 }"}

Merging with array concatenation

Merge-deep can also merge arrays by concatenating them. This is useful when you want to combine arrays from different objects without losing any elements.

{"const mergeDeep = require('merge-deep');\nconst object1 = { a: [1, 2], b: 'one' };\nconst object2 = { a: [3, 4], b: 'two' };\nconst result = mergeDeep(object1, object2);\nconsole.log(result); // Output: { a: [1, 2, 3, 4], b: 'two' }"}

Customizing merge behavior

Users can define a custom merge function to control how merging is done. This is particularly useful when the default behavior of merge-deep does not suit the specific needs of your application.

{"const mergeDeep = require('merge-deep');\nfunction customMerge(a, b) {\n  return Array.isArray(a) ? a.concat(b) : undefined;\n}\nconst object1 = { a: [1], b: [2] };\nconst object2 = { a: [3], b: [4] };\nconst result = mergeDeep({ customMerge }, object1, object2);\nconsole.log(result); // Output: { a: [1, 3], b: [2, 4] }"}