Benchmark: Object.hasOwn VS `in` [simple]

Script Preparation code:

function makeid() {
  var text = "";
  var possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  for (var i = 0; i < 5; i++)
    text += possible.charAt(Math.floor(Math.random() * possible.length));

  return text;
}

window.parentObj = {};

for (let i = 0; i < 100; i++) {
	window.parentObj[makeid()] = makeid();
}

Tests:

in
const obj = window.parentObj; for (const k of Object.keys(obj)) { k in obj; }
Object.hasOwn
const obj = window.parentObj; for (const k of Object.keys(obj)) { Object.hasOwn(obj, k); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
in
Object.hasOwn

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

LLMs can make mistakes. Check important info.

I'll explain what's being tested in the provided benchmark.

**Benchmark Overview**

The test compares the performance of two ways to check if an object has a property: using the `in` operator and using the `Object.hasOwn` method.

**Options Compared**

1. **`in` Operator**: The `in` operator is used to check if a key exists in an object. It returns a boolean value indicating whether the key is present in the object.
2. **`Object.hasOwn` Method**: The `Object.hasOwn` method is a built-in JavaScript method that checks if an object has a property with the given name.

**Pros and Cons**

* **`in` Operator**:
	+ Pros: Simple, intuitive syntax; works for most cases.
	+ Cons: May not be as efficient as other methods, especially when dealing with large objects or complex property names. Can also lead to unexpected behavior if used incorrectly (e.g., checking for undefined properties).
* **`Object.hasOwn` Method**:
	+ Pros: More explicit and controlled way of checking property existence; can provide better performance in certain cases.
	+ Cons: May require more code to achieve the same result as using the `in` operator.

**Library Used**

None. The test uses only built-in JavaScript methods and operators.

**Special JS Feature/Syntax**

There is no special JS feature or syntax used in this benchmark. Both `in` and `Object.hasOwn` are standard methods that have been part of the JavaScript language since its inception.

**Other Alternatives**

In addition to the `in` operator and `Object.hasOwn` method, other alternatives for checking property existence include:

* Using `hasOwnProperty()` on the object (e.g., `obj.hasOwnProperty(k)`): This method is similar to `Object.hasOwn`, but is specific to the owning object.
* Using a custom implementation (e.g., iterating over the object's own enumerable properties using `for...in` or `for...of`): These approaches can be more efficient in certain cases, but may require more code and may not be as readable.

It's worth noting that the choice of which method to use depends on the specific requirements of your use case. If you need a simple and straightforward way to check property existence, using the `in` operator or `hasOwnProperty()` might be sufficient. However, if you need more control over the checking process or performance optimization, using `Object.hasOwn` or implementing a custom solution might be a better choice.

Related benchmarks:

Object.hasOwn VS `in` [simple] (version: 0)

Comparing performance of: in vs Object.hasOwn

Created: 3 years ago by: Guest

Jump to the latest result

in

Object.hasOwn

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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