Benchmark: instanceof vs hasOwnProperty2

Script Preparation code:

var obj = {a: 1}

Tests:

instanceOf
obj instanceof Object
hasOwnProperty
obj.hasOwnProperty('b')

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
instanceOf
hasOwnProperty

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 the provided benchmark definition and test cases to understand what's being tested.

**Benchmark Definition**

The provided JSON represents a JavaScript microbenchmark named "instanceof vs hasOwnProperty2". This benchmark is testing two different approaches: `obj instanceof Object` and `obj.hasOwnProperty('b')`.

**Script Preparation Code**

The script preparation code is:
```javascript
var obj = {a: 1};
```
This creates an object `obj` with a single property `a` containing the value `1`. The properties of this object are not explicitly defined, so they will be inherited from the prototype chain.

**Html Preparation Code**

The html preparation code is empty (`null`). This means that no HTML-related setup or teardown is required for these benchmark tests.

**Individual Test Cases**

There are two individual test cases:

1. `obj instanceof Object`:
This test case checks whether the object `obj` is an instance of the `Object` constructor. In JavaScript, a value is considered an instance of a constructor if it has the prototype property and its prototype's constructor is that constructor.

2. `obj.hasOwnProperty('b')`:
This test case checks whether the object `obj` has a property named `b`. The `hasOwnProperty` method returns true if the object has the specified property as its own property (i.e., not inherited from the prototype chain).

**Pros and Cons of Approaches**

The two approaches being tested have different pros and cons:

* **`obj instanceof Object`:**
	+ Pros:
		- Simple and straightforward check.
		- Works for objects with inherited properties.
	+ Cons:
		- May return false positives (i.e., objects that are not instances of `Object`) due to the object's prototype chain.
		- Can be slower for large objects or complex prototypes.
* **`obj.hasOwnProperty('b')`:**
	+ Pros:
		- Returns true only if the property is an own property, avoiding false positives.
		- May be faster than the `instanceof` check due to its simplicity.
	+ Cons:
		- Returns false negatives (i.e., objects that have inherited properties) unless explicitly checking for those.

**Library and Purpose**

There are no specific libraries mentioned in the provided benchmark definition. However, it's worth noting that some JavaScript engines or browsers might use optimized implementations of `hasOwnProperty` or `instanceof`, which could affect the results.

**Special JS Feature or Syntax**

The test cases do not appear to utilize any special JavaScript features or syntax beyond standard ECMAScript language and APIs.

**Other Alternatives**

For a similar benchmark, you might consider testing other approaches, such as:

* Using a library like `lodash` for optimized property checks (e.g., `_.has(obj, 'b')`)
* Utilizing browser-specific optimizations or features (e.g., WebAssembly)
* Implementing custom, hand-optimized code using assembly-like languages
* Measuring performance under different conditions (e.g., memory constraints, CPU-bound scenarios)

Keep in mind that the specific approach and optimization techniques used can depend on the target JavaScript engine, hardware platform, and use case.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.80 Safari/537.36

Browser/OS: Chrome 71 on Linux

View result in a separate tab

Test name	Executions per second
instanceOf	3302617.2 Ops/sec
hasOwnProperty	10371725.0 Ops/sec

Related benchmarks:

instanceof vs hasOwnProperty2 (version: 0)

Comparing performance of: instanceOf vs hasOwnProperty

Created: 5 years ago by: Guest

Jump to the latest result

instanceOf

hasOwnProperty

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):