Benchmark: in vs hasOwn - MeasureThat.net

Script Preparation code:

var obj = { a: 1, b: 2, c: 3, d: 4, e: 5 };

Tests:

in
'd' in obj;
hasOwn
Object.hasOwn(obj, 'd');

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
in
hasOwn

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 19 days ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36

Browser/OS: Chrome 131 on Linux

View result in a separate tab

Test name	Executions per second
in	39433436.0 Ops/sec
hasOwn	20501648.0 Ops/sec

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

LLMs can make mistakes. Check important info.

I'd be happy to help explain the JavaScript microbenchmark provided by MeasureThat.net.

**Benchmark Overview**

The benchmark compares the performance of two different ways to check if an object has a property: using the `in` operator and using the `hasOwn()` method. The test is designed to measure which approach is faster, but more importantly, it helps identify any potential performance bottlenecks in JavaScript code.

**Options Compared**

The benchmark compares the following two options:

1. **`d in obj`**: This uses the `in` operator to check if the object `obj` has a property named `d`. The `in` operator checks for both the presence and value of the property.
2. **`Object.hasOwn(obj, 'd')`**: This uses the `hasOwn()` method, which is part of the ECMAScript Object API, to check if the object `obj` has a property named `d`.

**Pros and Cons**

Here are some pros and cons of each approach:

* **`in` operator:**
	+ Pros:
		- Widely supported across browsers
		- Can be faster for simple checks (less overhead)
	+ Cons:
		- May not work correctly with non-enumerable properties or symbols
		- May return `true` if the property is a getter or setter function (not what you want in this case)
* **`hasOwn()` method:**
	+ Pros:
		- More explicit and readable
		- Avoids potential issues with non-enumerable properties or symbols
	+ Cons:
		- May be slower due to the extra overhead of calling a function

**Library and Purpose**

The `Object.hasOwn()` method is part of the ECMAScript Object API, which provides a standardized way for objects to interact. This method checks if an object has a property with the given name.

**Special JS Features or Syntax**

None mentioned in this benchmark.

**Other Alternatives**

There are other ways to check if an object has a property, such as:

* Using `Object.prototype.hasOwnProperty()` ( deprecated and removed from ECMAScript 5)
* Using a simple `if` statement: `if ('d' in obj) { ... }`
* Using a regex: `/^d$/`

However, these alternatives are not included in this benchmark.

**Benchmark Preparation Code**

The preparation code for the benchmark creates an object `obj` with five properties (`a`, `b`, `c`, `d`, and `e`). The script to be measured is then executed using the `in` operator or the `hasOwn()` method, depending on the test case.

**Individual Test Cases**

Each test case executes a single line of code: `'d' in obj;` or `Object.hasOwn(obj, 'd');`. These lines are designed to check if the object `obj` has a property named `d`.

The benchmark results show the performance metrics for each test case, including the number of executions per second.

I hope this explanation helps you understand what's happening in this JavaScript microbenchmark!

Related benchmarks:

in vs hasOwn (version: 0)

Object lookup performance Comparing performance of: in vs hasOwn

Comparing performance of: in vs hasOwn

Created: 7 months ago by: Guest

Jump to the latest result

in

hasOwn

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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