Benchmark: instanceof vs type

Script Preparation code:

class Something {
   constructor() {
     this.type = 'something'
   }
}

var s = new Something();

Tests:

type
return s && s.type === 'something';
instanceof
return s instanceof Something;

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
type
instanceof

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided JSON to understand what is being tested on MeasureThat.net.

**Benchmark Description**

The benchmark measures the performance difference between two JavaScript operators: `typeof` (also known as "instanceof" in some browsers) and the literal type comparison (`s.type === 'something'`).

**Script Preparation Code**

The script defines a class `Something` with a constructor that sets the `type` property to `'something'`. A variable `s` is then created by instantiating this class.

**Html Preparation Code**

There is no HTML preparation code provided, which means the benchmark only runs in a JavaScript context and doesn't involve any DOM interactions or rendering.

**Individual Test Cases**

The benchmark consists of two test cases:

1. **"type"`**: This test case checks whether `s` is truthy and its type is exactly `'something'`. The literal type comparison (`s.type === 'something'`) is used.
2. **"instanceof"`**: This test case checks whether the instance of `Something` is an instance of itself using the "instanceof" operator.

**Library**

There is no external library mentioned in this benchmark. It's a simple JavaScript implementation.

**Special JS Feature/Syntax**

The use of the literal type comparison (`s.type === 'something'`) and the "instanceof" operator are standard JavaScript features, but their behavior might vary across browsers or versions. However, in modern browsers, these operators behave similarly to the provided benchmark.

**Pros and Cons**

Here's a brief overview of the pros and cons for each approach:

* **Literal Type Comparison (`s.type === 'something'`)**:
	+ Pros: Simple, widely supported, and easy to understand.
	+ Cons: May not work correctly in older browsers or versions.
* **"Instanceof" Operator**:
	+ Pros: More explicit and type-safe than literal comparisons.
	+ Cons: May be slower due to the additional indirection.

**Other Alternatives**

If you wanted to test alternative approaches, here are a few ideas:

1. Use `instanceof` with `new`: `return s instanceof Something && new Something() === s`
2. Use a library like Lodash's `isEqual` function: `return _.isEqual(s, { type: 'something' })`
3. Test with different data types (e.g., numbers, booleans) to see how the operators handle them.

Keep in mind that these alternatives might change the benchmark's behavior or add unnecessary complexity. MeasureThat.net is already providing a well-designed and simple benchmark, so it's best to stick with the original implementation.

Latest run results:

Run details: (Test run date: 8 years ago)

User agent: Mozilla/5.0 (iPhone; CPU iPhone OS 9_3_5 like Mac OS X) AppleWebKit/601.1.46 (KHTML, like Gecko) Version/9.0 Mobile/13G36 Safari/601.1

Browser/OS: Mobile Safari 9 on iOS 9.3.5

View result in a separate tab

Test name	Executions per second
type	2617838.2 Ops/sec
instanceof	2559686.0 Ops/sec

Related benchmarks:

instanceof vs type (version: 0)

Comparing performance of: type vs instanceof

Created: 8 years ago by: Guest

Jump to the latest result

type

instanceof

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 26 days ago):