JS Built-ins
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ObjectisPrototypeOfintermediate

isPrototypeOf() — vs instanceof

📖 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() — comparison with instanceof

instanceof checks if Constructor.prototype is in the chain. isPrototypeOf() is more flexible — you can check any object, not just constructor prototypes.

Challenge: Use isPrototypeOf() to replicate what instanceof checks.

💡 Hints (1)
  • • isPrototypeOf is more general than instanceof — it can check any prototype, not just constructor.prototype