Infinite Method Object - Solution & Explanation

Problem Overview: Design a function createInfiniteObject() that returns an object capable of handling any method call. No matter which method name you access, calling it should return the method’s name as a string. The object must behave as if it has infinitely many methods defined.

Approach 1: Static Method Definitions (Naive Idea) (Time: O(1) per call, Space: O(n))

A straightforward but impractical idea is to explicitly define every method on the returned object. Each property would store a function that returns its own name. This works for a small, known set of methods, but the requirement here is that the object should support any method name. Predefining methods cannot scale to an infinite interface and defeats the purpose of the problem. While the invocation cost stays constant O(1), memory usage grows with the number of defined methods O(n). This approach demonstrates the expected behavior but fails the “infinite” requirement.

Approach 2: JavaScript Proxy for Dynamic Method Resolution (Time: O(1), Space: O(1))

The intended solution relies on the Proxy object in JavaScript. A proxy intercepts property access on an object using the get trap. Whenever a property is accessed (for example obj.hello), the trap receives the property name. Instead of returning a stored value, the proxy dynamically returns a function that closes over the property name and returns it when invoked.

This design makes the object effectively support infinite methods. Accessing obj.test(), obj.anything(), or obj.randomName() all trigger the same get handler. The handler generates a new function that returns the property name string. Since no methods are stored ahead of time, the object remains lightweight and flexible.

The key insight is that property access and method invocation are separate steps. First, the runtime looks up the property; second, it executes the returned function. The proxy intercepts the lookup step and injects a function that knows the method name. This pattern is common in dynamic APIs, fluent interfaces, and meta‑programming tasks involving objects and proxies.

Each lookup simply returns a small function closure, so the operation runs in constant time O(1) and requires constant extra space O(1). No precomputation or storage of method names is necessary.

Recommended for interviews: The Proxy-based solution is the expected answer. Interviewers want to see that you understand JavaScript’s meta‑programming capabilities and how property interception works. Mentioning the naive “define every method” idea shows you understand the requirement, but implementing the dynamic proxy demonstrates real JavaScript fluency.