Benchmark: for-in vs object.keys1

Script Preparation code:

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

Tests:

for-in
for (var key in obj) { console.log(key); }
Object.keys
Object.keys(obj).forEach(key => console.log(key));

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):

LLMs can make mistakes. Check important info.

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

**Benchmark Overview**

The benchmark compares two approaches to iterate over an object's properties: `for-in` loop and `Object.keys()` method.

**Options Compared**

Two options are compared:

1. **For-In Loop**: A traditional `for-in` loop iterates over an object's properties by accessing the property names using the `in` operator.
2. **Object.keys() Method**: The `Object.keys()` method returns an array of a given object's own enumerable property names.

**Pros and Cons**

Here are some pros and cons of each approach:

* **For-In Loop**:
	+ Pros: Simple, easy to understand, and widely supported.
	+ Cons: Can be slower due to the overhead of checking if the property is an own property using `in`, which can lead to unnecessary iterations. Additionally, it doesn't provide a way to get the actual value of the property.
* **Object.keys() Method**:
	+ Pros: Faster than the traditional `for-in` loop since it uses a V8-specific optimization that skips over non-enumerable properties and returns an array of only the enumerable property names.
	+ Cons: Can be less intuitive for beginners, as it requires knowing about the `Object.keys()` method.

**Library Used**

The benchmark doesn't use any external libraries. The `Object.keys()` method is a built-in JavaScript method that's available in most modern browsers and Node.js environments.

**Special JS Feature or Syntax**

There are no special JavaScript features or syntaxes being tested here, as both approaches only rely on standard JavaScript language constructs.

**Alternative Approaches**

Other alternatives to compare the performance of iterating over an object's properties could include:

1. **Using `for...of` Loop**: This is a newer iteration loop that was introduced in ECMAScript 2015 (ES6). It provides a more modern and concise way to iterate over iterable objects, including arrays and objects.
2. **Using Array.prototype.forEach()**: Instead of using `Object.keys()` or the traditional `for-in` loop, you could use `Array.prototype.forEach()` to iterate over an array of property names.

Keep in mind that these alternatives might not be as well-supported as the original approaches being compared, so it's essential to test them thoroughly before making any conclusions.

Related benchmarks:

for-in vs object.keys1 (version: 0)

Comparing performance of: for-in vs Object.keys

Created: 5 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):