Benchmark: Class instance method lookup vs function-created object method lookup

Script Preparation code:

window.AClass = class {
  b() {
    return 4;
  }
}

window.AFunc = function() {
  return {
    b() {
      return 4;
    }
  };
};

Tests:

Class instance method lookup
const a = new AClass(); a.b();
Function-created object method lookup
const a = new AFunc(); a.b();

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Class instance method lookup
Function-created object method lookup

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Benchmark Overview**

The benchmark is designed to compare two approaches: class instance method lookup and function-created object method lookup.

**Class Instance Method Lookup**

In this approach, an instance of the `AClass` class is created and its `b()` method is invoked directly on the instance. The `b()` method returns a value, which is then executed and measured by the benchmark.

This approach tests how JavaScript engines execute methods on objects that are instances of classes. It's essential to note that this type of lookup is commonly used in object-oriented programming (OOP) scenarios.

**Function-Created Object Method Lookup**

In this approach, an object is created using a function expression (`window.AFunc = function() {...}`), and its `b()` method is invoked directly on the object. The `b()` method also returns a value, which is then executed and measured by the benchmark.

This approach tests how JavaScript engines execute methods on objects that are not instances of classes but rather objects created using function expressions.

**Pros and Cons**

Both approaches have their pros and cons:

* Class instance method lookup:
	+ Pros: This approach is commonly used in OOP scenarios, and it's easy to understand the intent of the code.
	+ Cons: It may lead to slower execution times due to the need for additional overhead to find the correct method on the object.
* Function-created object method lookup:
	+ Pros: This approach can be faster since there's no need for additional overhead to find the correct method on the object. Additionally, it allows for more flexibility in creating objects with specific properties and methods.
	+ Cons: It may lead to confusion when reading code, especially if the function expression is complex.

**Library**

There doesn't appear to be any external library used in this benchmark.

**Special JS Features or Syntax**

There are no special JavaScript features or syntaxes being tested in this benchmark. The focus is on understanding how different approaches affect performance.

**Other Alternatives**

To create a similar benchmark, you could consider the following alternatives:

* Using prototypes and `this` keyword to test method invocation on objects.
* Creating an object using constructors (e.g., `new AFunc()`).
* Comparing the performance of function expressions versus constructor functions for creating objects.

Keep in mind that these alternatives might require adjustments to the benchmark's setup and script preparation code.

Latest run results:

Run details: (Test run date: 3 years ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:84.0) Gecko/20100101 Firefox/84.0

Browser/OS: Firefox 84 on Windows

View result in a separate tab

Test name	Executions per second
Class instance method lookup	68332160.0 Ops/sec
Function-created object method lookup	31726560.0 Ops/sec

Related benchmarks:

Class instance method lookup vs function-created object method lookup (version: 0)

Comparing performance of: Class instance method lookup vs Function-created object method lookup

Created: 3 years ago by: Guest

Jump to the latest result

Class instance method lookup

Function-created object method lookup

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 25 days ago):