Implementing a Hidden Class System in JavaScript

This challenge asks you to implement a simplified hidden class system in JavaScript, mimicking a common optimization technique used in high-performance JavaScript engines. Hidden classes allow for faster property access by leveraging the fact that objects often share the same structure (same properties in the same order) during their lifetime. This optimization avoids costly prototype chain lookups.

Problem Description

You need to create a HiddenClassSystem class that manages the creation and reuse of hidden classes. The system should provide the following functionality:

1. createObject(properties): This method takes an object as input, where properties is an array of strings representing the property names in the order they appear in the object. It should create a new object and assign it a hidden class. If a hidden class with the given property order already exists, it should reuse that class. If not, it should create a new hidden class and associate it with the object.

2. getHiddenClass(object): This method takes an object as input and returns the hidden class associated with it. If the object doesn't have a hidden class, it should return null.

3. getClassForProperties(properties): This method takes an array of strings representing property names in order and returns the hidden class associated with that property order. If no such class exists, it creates one and returns it.

4. destroy(): This method should clear all hidden classes from the system, effectively resetting it.

The hidden class system should internally manage a map (or similar data structure) to store hidden classes, keyed by the property order (represented as a string). Each hidden class should be a simple object with no properties other than a unique identifier (e.g., a number). The identifier is purely for internal tracking and should not be exposed.

Expected Behavior:

• Objects created with the same property order should share the same hidden class.
• Objects created with different property orders should have different hidden classes.
• getHiddenClass should return the correct hidden class for a given object.
• destroy should clear all hidden classes.

Edge Cases to Consider:

• Empty properties array.
• Duplicate property names in the properties array. (The order matters, so duplicates are valid.)
• Large number of properties.
• Multiple calls to createObject with the same property order.
• getHiddenClass on an object that was not created by createObject.

Examples

Example 1:

Input:
const system = new HiddenClassSystem();
const obj1 = system.createObject(['a', 'b']);
const obj2 = system.createObject(['a', 'b']);
const obj3 = system.createObject(['b', 'a']);

Output:
system.getHiddenClass(obj1) === system.getHiddenClass(obj2) // true
system.getHiddenClass(obj1) !== system.getHiddenClass(obj3) // true

Explanation: obj1 and obj2 share the same hidden class because they have the same property order. obj3 has a different property order and therefore a different hidden class.

Example 2:

Input:
const system = new HiddenClassSystem();
const obj1 = system.createObject(['a']);
const obj2 = system.createObject(['a', 'b']);
const obj3 = system.createObject(['a', 'b', 'c']);

Output:
system.getHiddenClass(obj1) !== system.getHiddenClass(obj2) // true
system.getHiddenClass(obj2) !== system.getHiddenClass(obj3) // true

Explanation: Each object has a unique property order, resulting in distinct hidden classes.

Example 3: (Edge Case)

Input:
const system = new HiddenClassSystem();
const obj1 = system.createObject([]);
const obj2 = system.createObject([]);
const obj3 = system.createObject(['a']);

Output:
system.getHiddenClass(obj1) === system.getHiddenClass(obj2) // true
system.getHiddenClass(obj1) !== system.getHiddenClass(obj3) // true

Explanation: Empty property arrays result in the same hidden class.

Constraints

• The properties array in createObject can contain up to 100 strings.
• Each string in the properties array will be a valid JavaScript identifier (alphanumeric characters and underscores).
• The HiddenClassSystem should be reasonably efficient in terms of memory usage. Avoid excessive object creation.
• The hidden class identifier should be unique for each hidden class created.

Notes

• You don't need to implement the actual property access optimization. The focus is on managing the hidden classes themselves.
• Consider using a Map or Object to store the hidden classes, keyed by a string representation of the property order.
• The string representation of the property order should be consistent across calls. A simple properties.join(',') is sufficient.
• Think about how to handle the destroy method efficiently.
• The hidden class itself is just a placeholder object; its internal structure is not important. A simple {} is fine.