utils-merge

const merge = require('utils-merge'); // CommonJS import for Node.js environments // Define initial objects let userProfile = { id: 'user123', name: 'Jane Doe', settings: { theme: 'dark', notifications: { email: true, sms: false } } }; let defaultProfileSettings = { language: 'en-US', settings: { notifications: { email: false, push: true }, // This will completely replace userProfile.settings.notifications privacy: { dataSharing: false } }, status: 'active' }; console.log('Initial User Profile:', JSON.stringify(userProfile, null, 2)); console.log('Default Settings to Merge:', JSON.stringify(defaultProfileSettings, null, 2)); // Perform the merge operation // WARNING: utils-merge performs a shallow merge and mutates the destination object. // Nested objects from the source will replace the corresponding nested objects in the destination, // rather than merging their properties recursively. merge(userProfile, defaultProfileSettings); console.log('\nUser Profile After Shallow Merge (destination mutated):', JSON.stringify(userProfile, null, 2)); // Example of shallow merge for nested objects: let objA = { config: { timeout: 1000, retries: 3 } }; let objB = { config: { timeout: 5000, maxAttempts: 5 } }; console.log('\nBefore nested merge: objA =', JSON.stringify(objA)); merge(objA, objB); console.log('After nested merge (config from objB replaced objA.config): objA =', JSON.stringify(objA)); // To create a new object without mutating the original 'userProfile' while using utils-merge: // First, create a shallow copy of 'userProfile' (or an empty object), // then merge the defaults into that copy. let newMergedProfile = merge({}, userProfile); merge(newMergedProfile, defaultProfileSettings); // Note: This example is illustrative. For true deep merge, other libs are needed. console.log('\nNew merged profile (via cloning then merging):', JSON.stringify(newMergedProfile, null, 2));