Benchmark: Instanceof vs string comparison vs property checking vs constructor comparison 2

HTML Preparation code:

<script>
class TestClass {
    constructor() {
        this.a = 2;
  
        this.b = 'hello';
        this.c = ['some','thing'];
        this.d = [1,1,2,3,5,8,13,21];
        this.e = 'foofoofoo';
        this.f = 'barbarbar';
        this.g = {foo:'bar',12:34};
        this.h = {nested:{nestedMore:{nestedEvenMore:'nah'}}};
  
        this.t = 'mesh';
    }
}
</script>

Script Preparation code:

var obj = new TestClass();

Tests:

instanceof
obj instanceof TestClass;
string type
obj.t === 'mesh'
string type + undefined
obj.t !== undefined
property
obj.a !== undefined
constructor comparison
obj.constructor === TestClass

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof
string type
string type + undefined
property
constructor comparison

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:78.0) Gecko/20100101 Firefox/78.0

Browser/OS: Firefox 78 on Mac OS X 10.11

View result in a separate tab

Test name	Executions per second
instanceof	39507116.0 Ops/sec
string type	86508840.0 Ops/sec
string type + undefined	34966680.0 Ops/sec
property	33149456.0 Ops/sec
constructor comparison	40121508.0 Ops/sec

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is tested, compared, and their pros and cons.

**Benchmark Overview**

The provided JSON represents a JavaScript microbenchmark created using MeasureThat.net. The benchmark compares the performance of four different approaches:

1. `instanceof` operator
2. Comparing a basic string type (using `===`)
3. Property checking (`obj.a !== undefined`)
4. Constructor comparison (`obj.constructor === TestClass`)

**Test Case Breakdown**

Each test case is represented by an object that contains the following information:

* `Benchmark Definition`: The actual JavaScript code that performs the benchmark.
* `Test Name`: A human-readable name for the test case.

Here's a brief explanation of each test case:

1. `instanceof` operator: This test case measures the performance of using the `instanceof` operator to check if an object is an instance of a class or constructor.
2. Comparing a basic string type: This test case compares two strings for equality using `===`. The test case creates a complex string with multiple properties and checks if it's equal to another string.
3. Property checking (`obj.a !== undefined`): This test case checks if a property (`a`) exists on an object without performing any comparison. It's likely used to test the performance of null or undefined checks.
4. Constructor comparison (`obj.constructor === TestClass`): This test case compares the constructor of an object with another class.

**Library and Special JS Features**

In this benchmark, two libraries are not explicitly mentioned:

* None
* No special JavaScript features (like `let`, `const`, `arrow functions`, etc.) are used in the provided code.

However, if you notice the use of `class` keyword to define the `TestClass`, it's a modern JavaScript feature introduced in ECMAScript 2015 (ES6). The `class` keyword allows for more concise and readable way of defining classes compared to traditional constructor-based class definitions.

**Pros and Cons**

Here are some pros and cons of each approach:

1. `instanceof` operator:
	* Pros: Efficient, lightweight, and easy to implement.
	* Cons: May not be as accurate as other methods for certain use cases (e.g., when dealing with prototypes).
2. Comparing a basic string type (`===`):
	* Pros: Simple, efficient, and widely supported.
	* Cons: May perform unnecessary work if the strings are complex or have similar values.
3. Property checking (`obj.a !== undefined`):
	* Pros: Lightweight, easy to implement, and suitable for most use cases.
	* Cons: Does not check if the property value is a specific string, only its existence.
4. Constructor comparison (`obj.constructor === TestClass`):
	* Pros: Efficient and lightweight, but might be less readable than other methods.
	* Cons: May not work correctly with certain types of constructors (e.g., those that return an object).

**Other Alternatives**

If you need alternative approaches for these benchmarks, here are some suggestions:

1. For `instanceof` operator:
	* Use `typeof obj === 'object' && obj.constructor.name === 'TestClass'`
2. For comparing a basic string type (`===`):
	* Use `obj.t.localeCompare('mesh') > 0` (for locale-based comparisons)
3. For property checking (`obj.a !== undefined`):
	* Use `Object.prototype.hasOwnProperty.call(obj, 'a') && obj.a !== undefined`

Please note that these alternatives might not provide the same performance characteristics as the original benchmark.

**Best Practices and Considerations**

When writing benchmarks like this one:

1. Choose test cases that are representative of common use cases in your application.
2. Ensure that each test case is independent and does not interfere with others.
3. Use meaningful and descriptive variable names to improve readability.
4. Avoid using complex logic or side effects in the benchmark code.
5. Consider using a separate testing framework or library if you need more advanced features.

By following these best practices, you can create accurate and reliable benchmarks that help you optimize your JavaScript performance.

Related benchmarks:

Instanceof vs string comparison vs property checking vs constructor comparison 2 (version: 0)

Measure the performance of instanceOf operator vs comparing a basic string type. but more properties

Comparing performance of: instanceof vs string type vs string type + undefined vs property vs constructor comparison

Created: 3 years ago by: Guest

Jump to the latest result

instanceof

string type

string type + undefined

property

constructor comparison

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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