JS Practice — Built-in Objects

Object.assign() — apply defaults

📖 Usage Example

// Merge source into target
const target = { a: 1 }
Object.assign(target, { b: 2 })   // → { a: 1, b: 2 }

Use Object.assign() to copy properties from one or more source objects into a target object.

Object.assign() for default values

A common pattern is to merge user-supplied options over a defaults object, so any missing keys fall back to their default values.

Challenge: Implement applyDefaults(defaults, overrides) that returns a new object with defaults applied, then overridden by overrides.

applyDefaults({ color: 'red', size: 'M' }, { color: 'blue' })
// → { color: 'blue', size: 'M' }

💡 Hints (2)

• Pass a fresh `{}` as the first target so neither `defaults` nor `overrides` is mutated.
• Order matters: `Object.assign({}, defaults, overrides)` lets overrides win.