Benchmark: Array loop vs foreach vs map for update field in object

Script Preparation code:

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

Tests:

foreach
arr.forEach(function (item){ item.data = someFn(item.id); })
for
for (var i = 0, len = arr.length; i < len; i++) { arr[i].data = someFn(arr[i].id); }
map
arr.map(function(item){ item.data=someFn(item.id); return item; });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
foreach
for
map

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/136.0.0.0 Safari/537.36 Edg/136.0.0.0

Browser/OS: Chrome 136 on Windows

View result in a separate tab

Test name	Executions per second
foreach	697641.5 Ops/sec
for	363041.9 Ops/sec
map	473207.8 Ops/sec

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

LLMs can make mistakes. Check important info.

I'll break down the provided benchmark and explain what's being tested, compared, and considered.

**Benchmark Definition**

The website MeasureThat.net provides a JSON representation of a benchmark, which consists of:

1. **Script Preparation Code**: This code is executed once to prepare the test environment. In this case, it creates an array `arr` with 1000 objects, each containing an `id` property. It also defines a function `someFn(i)` that takes an `i` value and returns `i * 3 * 8`.
2. **Html Preparation Code**: This is empty in the provided benchmark.

**Individual Test Cases**

The benchmark has three test cases:

1. **foreach**
```javascript
arr.forEach(function (item) {
  item.data = someFn(item.id);
});
```
This test case uses the `forEach` method to iterate over the array and update each object's `data` property with the result of `someFn(item.id)`.

2. **for**
```javascript
for (var i = 0, len = arr.length; i < len; i++) {
  arr[i].data = someFn(arr[i].id);
}
```
This test case uses a traditional `for` loop to iterate over the array and update each object's `data` property with the result of `someFn(arr[i].id)`.

3. **map**
```javascript
arr.map(function(item) {
  item.data = someFn(item.id);
  return item;
});
```
This test case uses the `map` method to create a new array and update each object's `data` property with the result of `someFn(item.id)`.

**Comparison**

The benchmark is comparing the performance of these three approaches:

* **foreach**: Using the `forEach` method to iterate over the array.
* **for**: Using a traditional `for` loop to iterate over the array.
* **map**: Using the `map` method to create a new array and update each object's property.

**Pros and Cons**

Here are some pros and cons of each approach:

1. **foreach**
	* Pros:
		+ Concise and easy to read
		+ Iterates over the array in a natural way (i.e., from start to end)
	* Cons:
		+ May not be as efficient as other approaches due to the method call overhead
2. **for**
	* Pros:
		+ Can be more control-oriented and flexible
		+ Avoids the overhead of method calls
	* Cons:
		+ More verbose and harder to read than `foreach`
3. **map**
	* Pros:
		+ Creates a new array with transformed data, which can be useful for certain use cases
		+ Can be more efficient than `foreach` due to the way it uses iterators under the hood
	* Cons:
		+ Requires creating an additional array, which can increase memory usage

**Library and Special JS Feature**

The benchmark does not explicitly use any libraries or special JavaScript features beyond what's considered standard (ECMAScript 2015 and later).

**Other Alternatives**

If you want to explore other alternatives, here are a few:

1. **Array.prototype.reduce()**: Instead of using `forEach` or `for`, you could use the `reduce()` method to accumulate the results.
2. **Set-based operations**: If the array size is very large, using set-based operations (e.g., `new Set(arr.map(someFn)).values().toArray()`) might be more efficient.

Keep in mind that these alternatives may have different performance characteristics and trade-offs depending on your specific use case.

Related benchmarks:

Array loop vs foreach vs map for update field in object (version: 0)

Comparing performance of: foreach vs for vs map

Created: 6 years ago by: Guest

Jump to the latest result

foreach

for

map

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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