Benchmark: instanceof vs typeof vs attribute

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'
typeof and test attribute
typeof obj === 'object' && obj.a
attribte
obj.a !== undefined

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceof
typeof
typeof no function
typeof and test attribute
attribte

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided JSON represents a JavaScript microbenchmark that tests the performance of three different approaches to check if an object has a specific property or attribute: `instanceof`, `typeof`, and `attribute` checks.

**Options being compared**

*   `instanceof`: Verifies if an object is an instance of a particular constructor function. In this case, it's checking if the object `obj` is an instance of the `Object` constructor.
*   `typeof`: Returns the type of an object as a string. For example, `typeof obj` returns `"object"`.
*   `attribute` check: Verifies if an object has a specific property or attribute. In this case, it's checking if `obj.a` is truthy.

**Pros and Cons**

*   **Instanceof**: This approach can be slower because it involves a constructor function lookup, which can lead to additional overhead.
    *   Pros:
        +   More accurate for some cases (e.g., checking if an object has inherited properties)
    *   Cons:
        +   Slower due to constructor function lookup
*   **Typeof**: This approach is generally faster because it only checks the type of the object, without involving a constructor function lookup.
    *   Pros:
        +   Faster
        +   More concise
    *   Cons:
        +   Less accurate for some cases (e.g., checking if an object has inherited properties)
*   **Attribute check**: This approach is generally faster because it only checks the existence of the property or attribute, without involving a type check.
    *   Pros:
        +   Faster
        +   More concise
    *   Cons:
        +   Less accurate for some cases (e.g., checking if an object has inherited properties)

**Library and Special JavaScript Features**

There is no explicit library mentioned in the benchmark. However, the use of `instanceof` and `typeof` suggests that the benchmark is using built-in JavaScript features.

The use of `obj.a` in one of the test cases implies that the object `obj` has a property or attribute named `a`.

**Other Alternatives**

Some alternative approaches to checking if an object has a specific property or attribute include:

*   Using a library like Lodash's `hasOwnProperty` or `lodash.isObject`
*   Using a regex pattern to check for the existence of a property
*   Using a custom implementation involving a simple loop to iterate over the object's properties

However, these alternatives may not be as efficient or concise as using built-in JavaScript features like `instanceof`, `typeof`, and attribute checks.

**Benchmark Preparation Code Explanation**

The preparation code provided is:
```javascript
var obj = {a: 2};
```
This code creates an object `obj` with a single property `a` containing the value `2`. This object will be used as the test subject for the benchmark.

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 12; SM-A725F) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/106.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 106 on Android

View result in a separate tab

Test name	Executions per second
instanceof	1827554.2 Ops/sec
typeof	5609618.5 Ops/sec
typeof no function	2779546.2 Ops/sec
typeof and test attribute	2826648.5 Ops/sec
attribte	1855127.5 Ops/sec

Related benchmarks:

instanceof vs typeof vs attribute (version: 0)

Comparing performance of: instanceof vs typeof vs typeof no function vs typeof and test attribute vs attribte

Created: 2 years ago by: Guest

Jump to the latest result

instanceof

typeof

typeof no function

typeof and test attribute

attribte

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):