Benchmark: instanceof vs typeof vs fast typeof object2

Script Preparation code:

var obj = {a:2};

Tests:

instanceof
obj instanceof Object
typeof
typeof obj === 'object'
typeof object charAt
(typeof obj).charAt(0) === 'o'
typeof object [0]
(typeof obj)[0] === 'o'
typeof object startsWith
(typeof obj).startsWith('o')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof
typeof
typeof object charAt
typeof object [0]
typeof object startsWith

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

**Benchmark Overview**

The MeasureThat.net benchmark is designed to compare the performance of different approaches for checking if an object is of type `Object`. The benchmark tests four variations:

1. `instanceof Object`
2. `typeof obj === 'object'`
3. `(typeof obj).charAt(0) === 'o'`
4. `(typeof obj)[0] === 'o'`
5. `(typeof obj).startsWith('o')`

**Test Case 1: instanceof**

This test case checks if the object is an instance of `Object` using the `instanceof` operator.

Pros:

* Clear and concise syntax
* Widely supported by most browsers

Cons:

* May be slower than other approaches due to the overhead of the `instanceof` check
* Does not provide any information about the object's type beyond its class name

**Test Case 2: typeof obj === 'object'**

This test case checks if the object is of type `Object` using the `typeof` operator with a string literal `'object'`.

Pros:

* Fast and efficient
* Provides information about the object's type beyond its class name (specifically, that it's an object)

Cons:

* May not work correctly for all objects (e.g., arrays, functions)
* The string literal `'object'` is hardcoded, which may lead to issues if the benchmark needs to be updated

**Test Case 3: (typeof obj).charAt(0) === 'o'**

This test case checks if the object's type starts with `'o'` using a combination of `typeof` and the `.charAt()` method.

Pros:

* Fast and efficient
* Does not require a string literal, making it more flexible than Test Case 2

Cons:

* May be slower than other approaches due to the overhead of calling methods on an object
* The syntax is less intuitive than other approaches

**Test Case 4: (typeof obj)[0] === 'o'**

This test case checks if the object's type starts with `'o'` using a combination of `typeof` and array indexing.

Pros:

* Fast and efficient
* Does not require a string literal, making it more flexible than Test Case 2

Cons:

* May be slower than other approaches due to the overhead of calling methods on an object
* The syntax is less intuitive than other approaches

**Test Case 5: (typeof obj).startsWith('o')**

This test case checks if the object's type starts with `'o'` using a combination of `typeof` and the `.startsWith()` method.

Pros:

* Fast and efficient
* Does not require a string literal, making it more flexible than Test Case 2

Cons:

* May be slower than other approaches due to the overhead of calling methods on an object
* The syntax is less intuitive than other approaches

**Library Used: None**

The benchmark does not use any external libraries.

**Special JS Features/Syntax**

None mentioned in this explanation. However, it's worth noting that `instanceof` and `typeof` are built-in operators in JavaScript, so they do not rely on any external syntax or features.

**Alternatives**

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

* Using a function like `isPrototypeOf()` or `constructor.name`
* Using a library like `lodash.isPlainObject()`

However, these approaches may be slower or more complex than the methods tested in this benchmark.

Latest run results:

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

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/96.0.4664.45 Safari/537.36

Browser/OS: Chrome 96 on Linux

View result in a separate tab

Test name	Executions per second
instanceof	5006375.0 Ops/sec
typeof	14291533.0 Ops/sec
typeof object charAt	13409224.0 Ops/sec
typeof object [0]	13275491.0 Ops/sec
typeof object startsWith	13227580.0 Ops/sec

Related benchmarks:

instanceof vs typeof vs fast typeof object2 (version: 0)

Comparing performance of: instanceof vs typeof vs typeof object charAt vs typeof object [0] vs typeof object startsWith

Created: 2 years ago by: Guest

Jump to the latest result

instanceof

typeof

typeof object charAt

typeof object [0]

typeof object startsWith

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):