Benchmark: instanceof vs typeof vs !!value

Script Preparation code:

var obj = {a:2};

Tests:

instanceof
obj instanceof Object
typeof
typeof obj === 'object'
typeof no function
typeof obj === 'object' && typeof obj !== 'function'
!! value
!!obj.a

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof
typeof
typeof no function
!! value

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 what is tested in the provided JSON and explain the different options compared, their pros and cons, and other considerations.

**Benchmark Definition**

The benchmark definition json specifies four test cases:

* `instanceof obj instanceof Object`: Tests whether an object can be checked for prototype chain membership using the `instanceof` operator.
* `typeof obj === 'object'`: Tests whether the result of the `typeof` operator is `'object'`.
* `typeof obj === 'object' && typeof obj !== 'function'`: Tests whether the result of the `typeof` operator on an object that has a prototype chain is not `'function'`, and tests whether the result of the `typeof` operator on an object that does not have a prototype chain is `'object'`.
* `!!obj.a`: Tests whether a bitwise NOT operator (`!!`) applied to the value of `obj.a` returns `true`.

**Script Preparation Code**

The script preparation code sets up a variable `obj` with a single property `a` having a value of 2. This object is used in all four test cases.

**Html Preparation Code**

There is no HTML preparation code specified, which means the benchmark only tests JavaScript-related functionality and does not consider any UI or DOM elements.

**Options Compared**

The benchmark compares the following options:

* `instanceof` vs `typeof`
	+ **Pros**: `instanceof` can be more efficient for checking prototype chain membership, while `typeof` is more general-purpose.
	+ **Cons**: `instanceof` may not work correctly with objects that do not have a prototype chain (e.g., null or undefined).
* `typeof obj === 'object'`
	+ **Pros**: This test checks both the object type and the presence of a prototype chain.
	+ **Cons**: The result can be influenced by the value of `obj`, which may not always indicate the intended functionality.
* `typeof obj === 'object' && typeof obj !== 'function'`
	+ **Pros**: This test checks the object type while excluding function types, providing more specific information about the object's nature.
	+ **Cons**: The result can still be influenced by the value of `obj`, which may not always indicate the intended functionality.
* `!!obj.a`
	+ **Pros**: A simple and efficient way to check whether a value is truthy or falsy.
	+ **Cons**: This test only checks one specific property, and the result does not provide information about the object's type or prototype chain.

**Other Considerations**

* The benchmark uses Chrome 129 as the browser, which may affect the results due to the specific implementation of the JavaScript engine in that version.
* The `DevicePlatform` field indicates that the benchmark was run on a desktop device with Mac OS X 10.15.7.

**Alternatives**

Other alternatives for testing similar functionality include:

* Using the `Object.prototype.toString.call()` method, which can provide more information about an object's type and prototype chain.
* Using a library like Lodash, which provides functions like `isPlainObject()`, `isArray()`, etc., to test specific properties of objects.

Keep in mind that these alternatives may have different performance characteristics or implications for code readability.

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/129.0.0.0 Safari/537.36

Browser/OS: Chrome 129 on Mac OS X 10.15.7

View result in a separate tab

Test name	Executions per second
instanceof	8906126.0 Ops/sec
typeof	22144772.0 Ops/sec
typeof no function	11832039.0 Ops/sec
!! value	22448668.0 Ops/sec

Related benchmarks:

instanceof vs typeof vs !!value (version: 0)

Comparing performance of: instanceof vs typeof vs typeof no function vs !! value

Created: one month ago by: Guest

Jump to the latest result

instanceof

typeof

typeof no function

!! value

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):