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hardsenior2 min read Updated 2026-10-06T00:00:00.000Z #javascript #prototypes

How do you create an object without a prototype? ​

Answer ​

Objects delegate property lookup through a prototype chain. Classes provide friendlier syntax, but inheritance, property ownership, and this still follow the underlying prototype model.

For How do you create an object without a prototype?, start with the rule or behaviour, then anchor it in a small realistic example. Distinguish the default approach from the exceptions and name the observable outcome: correctness, maintainability, accessibility, performance, or security.

Example ​

js
function User(name) { this.name = name }
User.prototype.greet = function () { return `Hi, ${this.name}` }
const ada = new User("Ada")
ada.greet() // "Hi, Ada"

The method is shared through User.prototype, not copied into every instance.

How to structure your answer ​

  1. Define the concept in one or two sentences.
  2. Explain when you would use it and when you would choose an alternative.
  3. Walk through a small example, including an edge case.
  4. Close with how you would test or measure the result.

Common mistakes ​

  • Repeating a definition without connecting it to real code.
  • Treating an optimization or abstraction as a default rather than a trade-off.
  • Omitting lifecycle, error, cleanup, accessibility, or testing considerations when they apply.

Follow-up prompts ​

  • What failure mode would you expect if this were implemented incorrectly?
  • How would you test this behaviour?
  • What changes when the feature must scale to a larger application or team?

Interview tip ​

For this hard-level question, narrate your assumptions before coding. Interviewers can assess reasoning from a clear, bounded example much better than from a list of APIs.

Built for developers preparing for technical interviews.