Benchmark: for-in vs object.keys vs object.keys 2

Script Preparation code:

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

Tests:

for-in
for (let i = 10000; i > 0; i--) { for (let key in obj) { if (obj.hasOwnProperty(key)) { console.log(key); } } }
Object.keys
for (let i = 10000; i > 0; i--) { for (let keyArray = Object.keys(obj), i = keyArray.length - 1; i >= 0; i--) { console.log(keyArray[i]); } }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
for-in
Object.keys

Fastest: N/A

Slowest: N/A

Latest run results:

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

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Let's break down the provided benchmark and its test cases.

**Overview**

The benchmark, named "for-in vs object.keys vs object.keys 2", compares three different approaches to iterate over an array-like object (`obj`) with six properties:

1. `for-in`
2. `Object.keys` (with a single loop)
3. `Object.keys` (with two loops)

**Options Compared**

The options being compared are:

* **for-in**: Iterates over the object's properties using the `for...in` loop, which iterates over both inherited and own properties.
	+ Pros: Can handle objects with complex inheritance hierarchies.
	+ Cons: May include inherited properties that are not relevant to the specific iteration, leading to slower performance and increased overhead.
* **Object.keys**: Iterates over an array of property names using the `Object.keys()` method. This approach is faster than `for-in` because it only considers own properties.
	+ Pros: Faster and more efficient, as it doesn't include inherited properties.
	+ Cons: May not work correctly with objects that inherit from other objects or have complex inheritance hierarchies.
* **Object.keys (with two loops)**: Iterates over the array of property names using a single loop, which is repeated twice to iterate over all properties. This approach combines the benefits of `for-in` and `Object.keys`.
	+ Pros: Faster than `Object.keys`, as it avoids the overhead of an additional loop.
	+ Cons: Still includes inherited properties, but with less overhead.

**Library Usage**

The benchmark uses the built-in JavaScript method `Object.keys()` to retrieve an array of property names from the `obj` object. This is a standard library function that has been part of the ECMAScript specification since ECMAScript 2009.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntax used in this benchmark that require specific knowledge beyond basic JavaScript programming concepts.

**Other Alternatives**

If you wanted to include additional approaches, here are some alternatives:

* **for...of**: Iterates over an array-like object using the `for...of` loop, which is a more modern and efficient way to iterate over arrays and objects.
* **Array.prototype.forEach()**: Iterates over an array of property names using the `forEach()` method, which is similar to `Object.keys()`, but with less overhead.
* **Reflect.ownKeys()`: Iterates over an object's own properties using the `Reflect.ownKeys()` method, which is a newer API that provides more control over iteration.

Please note that these alternatives might not be directly comparable to the original three options, as they may have different performance characteristics or syntax requirements.

Related benchmarks:

for-in vs object.keys vs object.keys 2 (version: 0)

Comparing performance of: for-in vs Object.keys

Created: 6 years ago by: Guest

Jump to the latest result

for-in

Object.keys

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):