Benchmark: Array vs object performance by Dan 2

Script Preparation code:

   var arr = [];
    for (var i = 0; i < 1000; i++) {
      arr[i] = i;
    }
  
    function someFn(i) {
      return i * 3 * 8;
    }
	
	var obj = {};
	for (var i = 0; i < 1000; i++) {
      obj[i] = i;
    }

Tests:

Array for each
arr.forEach(function (item){ someFn(item); })
Array for
for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }
Array map
arr.map(item => someFn(item))
Object for each
Object.keys(obj).forEach(function(item) { someFn(item); });
Object for in
for (item in obj) { someFn(item); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Array for each
Array for
Array map
Object for each
Object for in

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark and explain what is being tested, the different approaches compared, their pros and cons, and other considerations.

**Benchmark Definition**

The provided benchmark definition is:

```javascript
{
  "Name": "Array vs object performance by Dan 2",
  "Description": null,
  "Script Preparation Code": "...",
  "Html Preparation Code": null
}
```

This script preparation code creates an array `arr` and an object `obj`, both initialized with 1000 elements. It also defines a function `someFn(i)` that takes an integer `i` as input and returns the result of multiplying `i` by 3 and 8.

**Individual Test Cases**

The benchmark consists of six individual test cases, each comparing a different approach:

1. **Array for each**: `arr.forEach(function (item) { someFn(item); })`
2. **Array for**: `for (var i = 0, len = arr.length; i < len; i++) { someFn(arr[i]); }`
3. **Array map**: `arr.map(item => someFn(item))`
4. **Object for each**: `Object.keys(obj).forEach(function(item) { someFn(item); })`
5. **Object for in**: `for (item in obj) { someFn(item); }`

**Approaches Compared**

The benchmark compares the performance of five different approaches:

1. **Array for each**: uses the `forEach` method to iterate over the array.
2. **Array for**: uses a traditional `for` loop to iterate over the array.
3. **Array map**: uses the `map` method to create a new array with transformed elements.
4. **Object for each**: uses the `forEach` method on an object's keys.
5. **Object for in**: uses the `for...in` loop to iterate over an object's properties.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

1. **Array for each**:
	* Pros: concise, easy to read.
	* Cons: can be slower than traditional loops due to overhead of `forEach`.
2. **Array for**:
	* Pros: control over iteration, no function call overhead.
	* Cons: more verbose, requires manual loop variable management.
3. **Array map**:
	* Pros: concise, efficient, and easy to read.
	* Cons: creates a new array, may not be suitable for large datasets.
4. **Object for each**:
	* Pros: concise, easy to read.
	* Cons: may not work as expected if object has non-enumerable properties.
5. **Object for in**:
	* Pros: control over iteration, no function call overhead.
	* Cons: less readable than `forEach`, requires manual property management.

**Other Considerations**

* The use of `arr.forEach` and `obj.forEach` implies that the benchmark is designed to measure performance on modern JavaScript engines that support these methods.
* The presence of `Object.keys` suggests that the benchmark may be interested in measuring the performance of iterating over object properties, which can be a complex topic due to various iteration modes (e.g., `for...in`, `forEach`).
* The use of `someFn(i)` as a test function implies that the benchmark is primarily focused on measuring the performance of array and object iteration, rather than specific JavaScript features or syntax.

**Alternatives**

Some alternative approaches for iterating over arrays and objects include:

* Using traditional loops (`for`, `while`)
* Using `every` method (e.g., `arr.every(function(item) { ... })`)
* Using `some` method (e.g., `arr.some(function(item) { ... })`)
* Using `reduce` method (e.g., `arr.reduce(function(accumulator, item) { ... })`)
* Using C-style iteration with pointers or iterators

Keep in mind that the choice of approach depends on the specific use case and performance requirements.

Latest run results:

Run details: (Test run date: 5 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.87 Safari/537.36

Browser/OS: Chrome 76 on Linux

View result in a separate tab

Test name	Executions per second
Array for each	11229.3 Ops/sec
Array for	6030.6 Ops/sec
Array map	10583.3 Ops/sec
Object for each	8712.3 Ops/sec
Object for in	2143.8 Ops/sec

Related benchmarks:

Array vs object performance by Dan 2 (version: 3)

Comparing performance of: Array for each vs Array for vs Array map vs Object for each vs Object for in

Created: 5 years ago by: Registered User

Jump to the latest result

Array for each

Array for

Array map

Object for each

Object for in

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated 29 days ago):