Benchmark: foreach vs filter+map

Script Preparation code:

var contacts = {
  'a1@a.com': {id: 1},
  'a2@a.com': {id: 2},
  'a3@a.com': {id: 3},
  'a4@a.com': {id: 4},
  'a5@a.com': {id: 5},
  'a6@a.com': {id: 6},
  'a7@a.com': {id: 7},
  'a8@a.com': {id: 8},
  'a9@a.com': {id: 9},
  'a10@a.com': {id: 10},
}

var selectedItems = [1,3,7];

Tests:

filter + map
Object.values(contacts).map(contact => contact.id).filter(id => selectedItems.indexOf(id) === -1)
forEach
Object.values(contacts).forEach((contact) => { if (selectedItems.indexOf(contact.id) === -1) { selectedItems.push(contact.id); } });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
filter + map
forEach

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 7 years ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36

Browser/OS: Chrome 60 on Mac OS X 10.12.6

View result in a separate tab

Test name	Executions per second
filter + map	419800.5 Ops/sec
forEach	490936.4 Ops/sec

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark is designed to compare two approaches for filtering an array of objects based on their IDs, which are stored in an object called `contacts`. The goal is to determine which approach is faster: using `forEach` or a combination of `filter` and `map`.

**Options Compared**

Two options are compared:

1. **`forEach`**: This approach uses the `forEach` method to iterate over the array of objects, checking if each object's ID is in the `selectedItems` array. If not, it adds the ID to the `selectedItems` array.
2. **`filter + map`**: This approach uses the `map` method to transform the `contacts` object into an array of IDs, and then uses the `filter` method to remove any IDs that are in the `selectedItems` array.

**Pros and Cons**

* **`forEach`**:
	+ Pros: Can be more straightforward for simple filtering tasks.
	+ Cons: May involve additional iterations or checks, which can slow down performance.
* **`filter + map`**:
	+ Pros: Can be optimized for faster lookup times using `map`.
	+ Cons: Requires creating an intermediate array of IDs, which can increase memory usage.

**Library and Purpose**

The `Object.values()` method is used to extract the values from the `contacts` object as an array. The purpose of this method is to provide a convenient way to work with objects in JavaScript.

**Special JS Feature or Syntax (None)**

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

**Other Considerations**

The benchmark assumes that the input data (`contacts`) and `selectedItems` arrays are already populated. It also doesn't account for any potential edge cases, such as empty arrays or invalid data.

**Alternative Approaches**

Other approaches to filtering an array of objects could include:

* Using a loop with `for...in` or `for...of` statements
* Utilizing modern JavaScript features like `Array.prototype.some()` or `Array.prototype.find()`
* Employing more advanced optimization techniques, such as memoization or caching

It's worth noting that the choice of approach ultimately depends on the specific requirements and constraints of the project. The benchmark is designed to provide a baseline comparison between two common approaches, but other options may be suitable depending on the context.

Related benchmarks:

foreach vs filter+map (version: 0)

Comparing performance of: filter + map vs forEach

Created: 7 years ago by: Guest

Jump to the latest result

filter + map

forEach

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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