JS Practice — Built-in Objects

hasOwnProperty() — basics

📖 Usage Example

// Check for own (non-inherited) property
const obj = { a: 1 }
obj.hasOwnProperty('a')          // → true
obj.hasOwnProperty('toString')   // → false

Use hasOwnProperty() to check whether a property exists directly on an object rather than on its prototype chain.

Object.prototype.hasOwnProperty()

obj.hasOwnProperty(key) returns true if the object has the specified key as its own (not inherited) property.

Challenge: Implement isOwnProperty(obj, key) that returns whether the key is an own property of the object.

💡 Hints (1)