Benchmark: member vs toStringTag

Script Preparation code:

var A = class A {
	_class = "A";
    
    [Symbol.toStringTag] = "A"
}

var isA1 = (obj) => {
	return obj._class === "A"
}

var isA2 = (obj) => {
	return String(obj) === "[object A]"
}

var a = new A()

Tests:

member
var b = isA1(a)
toStringTag
var b = isA2(a)

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
member
toStringTag

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

Let's dive into the Benchmark Definition and Individual test cases.

**Benchmark Definition**

The benchmark measures the performance difference between two approaches to check if an object is of type `A`. There are two test cases:

1. **Member**: `var b = isA1(a)`, where `isA1` checks if the object's `_class` property equals `"A"`.
2. **toStringTag**: `var b = isA2(a)`, where `isA2` checks if the string representation of the object (using `String(obj)` or `${obj}`) equals `"[object A]"`.

**Options Compared**

The two options being compared are:

1. Checking the `_class` property directly (`isA1`) versus
2. Using the `toStringTag` property to get the string representation of the object (`isA2`).

**Pros and Cons of Each Approach**

**Directly Checking `_class` Property (isA1)**

Pros:

* Fast, as it only accesses a single property.
* No unnecessary string creation or lookup.

Cons:

* May not work correctly if the object's class is not properly set or if there are other classes with the same name in inheritance hierarchies.
* May require additional setup to ensure accurate results (e.g., checking for correct inheritance).

**Using `toStringTag` Property (isA2)**

Pros:

* Robust, as it works regardless of the object's class or inheritance hierarchy.
* Can be used to verify the presence of a specific class or prototype chain.

Cons:

* Slower, as it involves creating a string representation of the object and comparing it to a fixed value.
* May introduce performance overhead due to unnecessary string creation.

**Other Considerations**

Both approaches assume that the `Symbol.toStringTag` property is properly set on objects of type `A`. This property is not enabled by default in some browsers (e.g., older versions of Chrome or Firefox).

**Library Used**

There is no explicit library mentioned in the benchmark definition. However, it's likely that the `class A` syntax and the use of `Symbol.toStringTag` are relying on ES6+ features, which are implemented natively in most modern browsers.

**Special JS Features/Syntax**

The benchmark uses ES6+ features, such as:

* Classes (`var A = class A { ... }`)
* Symbol properties (`[Symbol.toStringTag]`)
* Template literals (`${obj}`)

These features are widely supported in modern browsers and can be used to create concise and expressive code.

**Alternatives**

Other alternatives for checking if an object is of type `A` might include:

1. Using a prototype chain check (e.g., `Object.getPrototypeOf(a) === A.prototype`)
2. Implementing a custom class hierarchy system
3. Using a third-party library or function to perform the check

However, these approaches may not offer the same level of simplicity and performance as the `Symbol.toStringTag` approach used in this benchmark.

Related benchmarks:

member vs toStringTag (version: 0)

Comparing performance of: member vs toStringTag

Created: 2 years ago by: Registered User

Jump to the latest result

member

toStringTag

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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