Benchmark: for-in hasOwnProperty vs object.keys test vs for-in

Script Preparation code:

var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};

Tests:

for-in hasOwnProperty
for (var i=10000; i > 0; i--) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) { console.log(key); } } }
Object.keys
for (var i=10000; i > 0; i--) { Object.keys(obj).forEach(key => console.log(key)); }
for-in
for (var i=10000; i > 0; i--) { for (var key in obj) { console.log(key); } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in hasOwnProperty
Object.keys
for-in

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what's being tested.

**Overview**

The test measures the performance of three different approaches to iterate over an object's keys:

1. `for-in` with `hasOwnProperty`
2. `Object.keys()`
3. Simple `for-in`

**What's being tested?**

Each test case is designed to run 10,000 iterations using a predefined object (`obj`) with six properties. The tests compare the execution time of each approach:

* **`for-in hasOwnProperty`**: Uses the `hasOwnProperty()` method to filter out inherited properties and only logs the keys that are directly owned by the object.
* **`Object.keys()`**: Utilizes the `Object.keys()` function, which returns an array of all keys in the object. This approach is expected to be faster since it doesn't require filtering.
* **Simple `for-in`**: Iterates over all properties using the `for-in` loop without any filtering or optimization.

**Pros and Cons**

1. **`for-in hasOwnProperty`**:
	* Pros: It filters out inherited properties, which can improve performance for large objects with complex inheritance hierarchies.
	* Cons: The filtering step introduces additional overhead, making it potentially slower than `Object.keys()` for simple cases.
2. **`Object.keys()`**:
	* Pros: Returns all keys in an array, allowing for easier iteration and filtering (in this case, no filtering is needed).
	* Cons: May incur a higher overhead due to the function call and array creation.
3. **Simple `for-in`**:
	* Pros: Simple and straightforward implementation with minimal overhead.
	* Cons: Iterates over all properties without any filtering or optimization, potentially leading to slower performance for large objects.

**Library/Library Purpose**

The test uses the `Object.keys()` function from the ECMAScript Standard Library. This function is a built-in method that returns an array of strings containing the property names in the specified object (in this case, `obj`).

**Special JS Features/Syntax**

There are no special JavaScript features or syntaxes being tested in this benchmark.

**Other Alternatives**

If you're looking for alternative approaches to iterate over objects, consider:

* **Using a custom loop**: You can write a simple loop using the `in` operator and string comparison to achieve similar results.
* **Using a library like Lodash**: The Lodash library provides a `keys()` function that is equivalent to `Object.keys()`.
* **Using a different data structure**: If you're dealing with large objects, you might consider using a more efficient data structure like a trie or an indexed object.

Keep in mind that these alternatives may not be optimized for performance and should be carefully evaluated based on your specific use case.

Related benchmarks:

for-in hasOwnProperty vs object.keys test vs for-in (version: 0)

Comparing performance of: for-in hasOwnProperty vs Object.keys vs for-in

Created: 3 years ago by: Guest

Jump to the latest result

for-in hasOwnProperty

Object.keys

for-in

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):