JS Built-ins
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ObjectisPrototypeOfintermediate

isPrototypeOf() — null prototype

📖 Usage Example
// Check prototype chain membership
const proto = {}
const child = Object.create(proto)
proto.isPrototypeOf(child)   // → true
Object.prototype.isPrototypeOf(child)  // → true

Use isPrototypeOf() to check whether an object exists anywhere in the prototype chain of another object.

isPrototypeOf() — null prototype objects

Objects created with Object.create(null) have no prototype. Object.prototype.isPrototypeOf() returns false for them.

Challenge: Verify that Object.prototype is not in the chain of a null-prototype object.

💡 Hints (1)
  • • Null-prototype objects have no inherited methods or prototype chain