JS Practice — Built-in Objects

propertyIsEnumerable() — inherited property

📖 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() — inherited properties

propertyIsEnumerable() always returns false for inherited properties, even if they are enumerable on the prototype.

Challenge: Show that inherited properties return false even when enumerable on the prototype.

💡 Hints (1)

• propertyIsEnumerable only considers own properties