Benchmark: for-in vs object.keys 22

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) { } }
Object.keys
for (var i=10000; i > 0; i--) { Object.keys(obj) }

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 provided benchmark and explain what's being tested, the options compared, their pros and cons, and other considerations.

**Benchmark Definition**
The benchmark is designed to compare the performance of two approaches: using `for...in` loop and `Object.keys()` method in JavaScript. The script preparation code creates an object `obj` with 22 properties, all initialized with the value `1`.

**Script Preparation Code**
```javascript
var obj = {
  'a': 1,
  'b': 1,
  'c': 1,
  'd': 1,
  'e': 1,
  'f': 1,
  'g': 1
};
```
This code creates an object `obj` with 22 properties, all initialized with the value `1`. This object will be used as input for both test cases.

**Individual Test Cases**
There are two test cases:

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

```javascript
for (var i=10000; i > 0; i--) {
  for (var key in obj) {
    // empty loop body
  }
}
```
This test case uses a traditional `for...in` loop to iterate over the properties of the object `obj`. The loop variable `key` takes on the value of each property name, and the loop body is intentionally left empty.

### Test Case 2: `Object.keys()`

```javascript
for (var i=10000; i > 0; i--) {
  Object.keys(obj)
}
```
This test case uses the `Object.keys()` method to get an array of property names of the object `obj`. The `Object.keys()` method returns a new array containing the property names as strings, which is then assigned to the variable `obj`.

**Pros and Cons**

* **for-in**: Pros:
	+ Can be more efficient in some cases, since it doesn't create an intermediate array.
	+ May be faster for large objects with many properties.
* Cons:
	+ Requires a loop body (although an empty one), which can introduce overhead.
	+ Can lead to slower performance if the loop body is complex or expensive.
* **Object.keys()**: Pros:
	+ Creates an intermediate array, but this array is likely to be small and cached by the browser.
	+ Can be faster for objects with a limited number of properties.
* Cons:
	+ Requires creating an intermediate array, which can lead to slower performance for large objects.
	+ May lead to increased memory usage.

**Library: None**

There are no external libraries used in this benchmark. The `Object.keys()` method is a built-in JavaScript function that returns an array of property names of the object it's called on.

**Special JS Feature/Syntax: None**

This benchmark does not use any special JavaScript features or syntax, such as async/await, generators, or closures. It only relies on standard JavaScript constructs and built-in methods.

**Alternatives**

Other alternatives to compare performance could include:

* Using `for...of` loop instead of `for...in`
* Using `forEach()` method instead of a traditional loop
* Using `Array.prototype.forEach()` method instead of a traditional loop
* Comparing the performance of using object literals (`{}`) versus objects with inherited properties

These alternatives could be explored to provide additional insights into the performance characteristics of different JavaScript constructs and methods.

Related benchmarks:

for-in vs object.keys 22 (version: 0)

Comparing performance of: for-in vs Object.keys

Created: 3 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):