JS Practice — Built-in Objects

propertyIsEnumerable() — after defineProperty with enumerable:false

📖 Usage Example

// Check if a property shows up in for...in loops
const obj = { a: 1 }
obj.propertyIsEnumerable('a')   // → true
Object.defineProperty(obj, 'b', { value: 2, enumerable: false })
obj.propertyIsEnumerable('b')   // → false

Use propertyIsEnumerable() to check whether a specific own property will appear during enumeration (e.g., for...in or Object.keys).

propertyIsEnumerable() — changing enumerability

You can change enumerability of an existing property with Object.defineProperty.

Challenge: Change a property from enumerable to non-enumerable and verify with propertyIsEnumerable().

💡 Hints (1)

• Enumerability can be toggled with defineProperty on configurable properties