Object Spread

// Create a new object with updated values
const original = { name: 'Alice', age: 30 }
const updated = { ...original, age: 31 }
// updated = { name: 'Alice', age: 31 }
// original is unchanged!

Order Matters

const defaults = { theme: 'light', fontSize: 14 }
const userPrefs = { fontSize: 18 }
const settings = { ...defaults, ...userPrefs }
// { theme: 'light', fontSize: 18 }

Nested Objects

const user = { name: 'Alice', address: { city: 'NYC' } }
const updated = {
	...user,
	address: { ...user.address, city: 'LA' },
}

1. Create updatedUser by spreading user and setting email to 'alice.new@example.com' — leave the original user unchanged
2. Create finalConfig by merging defaultConfig then userConfig so user values win (timeout should be 10000, other fields from defaults)
3. Create userWithDarkMode by immutably updating nested settings.theme to 'dark' while keeping notifications: true — leave user.settings.theme as 'light'
4. Export updatedUser, user, finalConfig, and userWithDarkMode