Benchmark: Instanceof VS toString for date comparison when using objects

Script Preparation code:

a = {};

Tests:

instanceof
a instanceof Date
prototype.toString
Object.prototype.toString.call(a) === '[object Date]'

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof
prototype.toString

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The first part of the JSON represents the overall benchmark definition, which includes:

* `Name`: A unique name for the benchmark, "Instanceof VS toString for date comparison when using objects".
* `Description`: An empty string, indicating that there is no descriptive text for this benchmark.
* `Script Preparation Code` and `Html Preparation Code`: These fields are empty, suggesting that no custom setup or HTML code needs to be executed before running the benchmarks.

**Individual Test Cases**

The second part of the JSON represents individual test cases, which include:

* `Benchmark Definition`: A string representing a specific JavaScript expression being tested.
	+ `a instanceof Date` : Tests whether the `instanceof` operator returns true when comparing an object with `Date`.
	+ `Object.prototype.toString.call(a) === '[object Date]'` : Tests whether the `toString()` method, accessed through `prototype`, returns the expected string representation for a `Date` object.
* `Test Name`: A descriptive name for each test case.

**Pros and Cons of Approaches**

The two approaches being compared are:

1. **`instanceof` operator**: This approach uses the built-in `instanceof` operator to check if an object is an instance of the `Date` class.
	+ Pros:
		- Efficient, as it directly checks the object's type without unnecessary string manipulation.
		- Simple and easy to understand.
	+ Cons:
		- May be slower due to the overhead of the `instanceof` operator.
2. **Using `prototype.toString()`**: This approach uses the `toString()` method accessed through the prototype chain to get a string representation of the object.
	+ Pros:
		- Can be faster for large objects, as it avoids the overhead of `instanceof`.
		- Still returns a string representation, making it easier to compare.
	+ Cons:
		- Requires accessing the `prototype` object and its `toString()` method, which might introduce additional overhead.

**Library: `Object.prototype.toString()`**

The library being used in this benchmark is `Object.prototype.toString()`. This function is part of the JavaScript Object Prototype (ECMAScript 3) specification. It returns a string representation of an object's constructor name or class name, depending on the object type.

In this context, `Object.prototype.toString.call(a)` is used to get a string representation of the object `a`, which should be in the format `[object Date]`. This allows for efficient comparison of the string representation with the expected value.

**Special JS Feature: None**

There are no special JavaScript features or syntax being tested in this benchmark. The focus is on comparing two straightforward approaches to checking if an object is a `Date` instance.

**Other Alternatives**

If you were to compare these approaches, some other alternatives could be:

1. **Using `Date.prototype.toString()`**: This approach uses the `toString()` method of the `Date` prototype instead of `Object.prototype.toString()`. While it might seem more specific, it's unlikely to provide any significant performance benefits.
2. **Using a custom implementation**: You could write your own function to convert an object to a string representation, potentially optimized for specific use cases or performance requirements.
3. **Using other comparison methods**: Depending on the context and requirements, you might want to explore alternative comparison methods, such as using `JSON.stringify()` or implementing a custom comparator function.

Keep in mind that these alternatives would likely introduce additional complexity and might not provide significant benefits over the simple `instanceof` operator and `prototype.toString()` approaches.

Latest run results:

Run details: (Test run date: 2 months ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/128.0.0.0 Safari/537.36

Browser/OS: Chrome 128 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
instanceof	10513417.0 Ops/sec
prototype.toString	9957124.0 Ops/sec

Related benchmarks:

Instanceof VS toString for date comparison when using objects (version: 0)

Comparing performance of: instanceof vs prototype.toString

Created: 2 months ago by: Guest

Jump to the latest result

instanceof

prototype.toString

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one month ago):