How does prototypal inheritance work?
PICTURE THIS: OOP PILLARS
Simple meaning
Objects have an internal prototype link used when a property is missing.
WHY — JavaScript instead of guessing?
Why interviewers care about JavaScript:
question about JavaScript.
trade-offs, and what you would actually do on a Frontend project - not buzzwords.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Objects have an internal
prototype link used when a property is missing.
- 2Why it exists
Constructors set instance.__proto__ to Constructor.prototype.
- 3ES6 class is sugar
over that same chain, which is why methods live on the prototype instead of each instance.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Objects have an internal prototype link used when a property is missing. Constructors set instance.__proto__ to Constructor.prototype.