JS Practice — Built-in Objects

hasOwnProperty() — inherited from Object.prototype

📖 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.

hasOwnProperty() — checking Object.prototype methods

Standard methods like toString, valueOf, and hasOwnProperty itself come from Object.prototype. They are NOT own properties of plain objects.

Challenge: Verify that standard Object.prototype methods are not own properties of plain objects.

💡 Hints (1)