Benchmark: for-in 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 (var i=10000; i > 0; i--) { for (var key in obj) { console.log(key); } }
Object.keys
for (var i=10000; i > 0; i--) { for (var key of Object.keys(obj)) { 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):

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

**Benchmark Overview**

The MeasureThat.net website allows users to create and run JavaScript microbenchmarks. The provided benchmark compares two approaches for iterating over an object: `for-in` and `Object.keys`. The benchmark measures which approach is faster on a specific device running Chrome 81 on Mac OS X 10.15.3.

**Benchmark Definition JSON**

The benchmark definition contains the following information:

* **Name**: "for-in vs object.keys - 2"
* **Description**: None
* **Script Preparation Code**: A script that defines an object `obj` with multiple properties, each initialized to 1.
* **Html Preparation Code**: None (not applicable in this case)

**Individual Test Cases**

The benchmark consists of two test cases:

### Test Case 1: "for-in"

The benchmark definition for the first test case is:
```javascript
for (var i=10000; i > 0; i--) {
  for (var key in obj) {
    console.log(key);
  }
}
```
This test case uses a traditional `for-in` loop to iterate over the properties of the `obj` object.

### Test Case 2: "Object.keys"

The benchmark definition for the second test case is:
```javascript
for (var i=10000; i > 0; i--) {
  for (var key of Object.keys(obj)) {
    console.log(key)
  }
}
```
This test case uses the `Object.keys` method to get an array of the object's property names and then iterates over that array using a `for...of` loop.

**Library:**

In both test cases, the `Object.keys` function is used to iterate over the properties of the `obj` object. The `Object.keys` function is a part of the JavaScript API and returns an array of the object's own enumerable property names.

**Special JS Feature/ Syntax:** None

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

**Pros and Cons of Different Approaches:**

1. **For-in Loop**: This approach has some advantages:
	* It can be used for iterating over both objects and arrays.
	* It provides access to the property name and value using the `in` operator.
However, it also has some disadvantages:
	* It is generally slower than other approaches due to its overhead.
2. **Object.keys Method**: This approach has some advantages:
	* It is faster than the traditional `for-in` loop.
	* It provides a way to iterate over an array of property names without having to use a loop.

However, it also has some disadvantages:
	* It can only be used for iterating over objects, not arrays.
	* It does not provide direct access to the property name and value like the `for-in` loop.

**Other Considerations:**

The benchmark uses a fixed object with multiple properties, all initialized to 1. This may not accurately represent real-world scenarios where objects can have varying sizes and complexities. Additionally, the benchmark only runs on Chrome 81 on Mac OS X 10.15.3, which is just one possible combination of browser, device platform, and operating system.

**Other Alternatives:**

There are other approaches that could be used to iterate over an object or array:

* Using a `for` loop with an index variable (e.g., `for (var i = 0; i < obj.length; i++) {}`)
* Using the `forEach` method
* Using a library like Lodash's `keys` function

However, the performance differences between these approaches are likely to be small compared to the traditional `for-in` loop and the `Object.keys` method.

Related benchmarks:

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