Benchmark: typeof vs instanceof vs constructor

Script Preparation code:

function Ticket(id) {
  this._id = id;
}

var testTicket = new Ticket(1);
var count = 1000;

Tests:

typeof check
for (var i = 0; i < count; i += 1) { if (typeof testTicket === 'object') { continue; } }
instanceof check
for (var i = 0; i < count; i += 1) { if (testTicket instanceof Ticket) { continue; } }
constructor check
for (var i = 0; i < count; i += 1) { if (testTicket.constructor.name === 'Ticket') { continue; } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
typeof check
instanceof check
constructor check

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/135.0.0.0 Safari/537.36

Browser/OS: Chrome 135 on Windows

View result in a separate tab

Test name	Executions per second
typeof check	438698.6 Ops/sec
instanceof check	293919.7 Ops/sec
constructor check	51633.4 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):

LLMs can make mistakes. Check important info.

**Overview**

The provided JSON represents a JavaScript benchmark test case, where the user compares the performance of three different approaches: `typeof`, `instanceof`, and `.constructor` property.

**Benchmark Purpose**

The benchmark tests how fast each approach can identify whether an object is a subclass of another object (in this case, `Ticket`) or not. The purpose of this test is to understand which approach is the most efficient in terms of performance.

**Options Compared**

There are three options compared:

1. `typeof`: This checks if the object is a constructor function using the `typeof` operator.
2. `instanceof`: This checks if the object is an instance of another object (in this case, `Ticket`) using the `instanceof` operator.
3. `.constructor.name === 'Ticket'`: This checks if the object's constructor has a property named `name` and its value is equal to `'Ticket'`.

**Pros and Cons of Each Approach**

1. `typeof`:
	* Pros: Simple and straightforward.
	* Cons: May not work as expected for certain types (e.g., arrays, functions).
2. `instanceof`:
	* Pros: More accurate than `typeof` for checking subclass relationships.
	* Cons: Can be slower due to the overhead of the `instanceof` operator.
3. `.constructor.name === 'Ticket'`:
	* Pros: Fast and efficient.
	* Cons: Requires access to the object's constructor property, which may not be available in all situations.

**Library Used**

The test case uses the `Ticket` class, which is a simple class definition provided by the benchmark author. The purpose of this class is to serve as a representative object for testing the `instanceof` operator.

**Special JS Feature or Syntax**

There is no special JavaScript feature or syntax used in this benchmark except for the use of the `instanceof` operator, which is a built-in operator in JavaScript.

**Other Considerations**

* The test case uses a small sample size (1000 executions) to measure performance.
* The benchmark runs on Firefox 131 and Windows desktop platforms.

**Alternatives**

If you wanted to compare these approaches using a different platform or browser, you could modify the `RawUAString` field in the benchmark result JSON to include additional information about the test environment. For example:

```
"RawUAString": "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:131.0) Gecko/20100101 Firefox/131.0 Safari/537.36 Chrome/91.0.4472.124"
```

This would allow you to compare the performance of each approach on different platforms and browsers using MeasureThat.net.

Related benchmarks:

typeof vs instanceof vs constructor (version: 0)

Comparing typeof vs instanceof vs .constructor property

Comparing performance of: typeof check vs instanceof check vs constructor check

Created: 2 years ago by: Guest

Jump to the latest result

typeof check

instanceof check

constructor check

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 6 months ago):