Benchmark: Object.groupBy vs manual groupBy

Script Preparation code:

function groupBy(array, mapper) {
    return array.reduce(
        (acc, item) => {
            const key = mapper(item);
            const items = acc[key] ?? (acc[key] = []);
            items.push(item);
            return acc;
        }, {},
    );
}

var data = [{
        name: "John",
        age: 20,
        occupation: null,
    },
    {
        name: "Jane",
        age: 30,
        occupation: "student",
    },
    {
        name: "Jack",
        age: 40,
        occupation: "student",
    },
    {
        name: "Simon",
        age: 50,
        occupation: "student",
    },
    {
        name: "Mary",
        age: 60,
        occupation: null,
    },
    {
        name: "George",
        age: 70,
        occupation: "influencer",
    },
]

Tests:

Object.groupBy
return Object.groupBy(data, item => item.occupation)
Manual groupBy
return groupBy(data, item => item.occupation)

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 6 runs

Manual groupBy

9.0M/s

Object.groupBy

3.6M/s

Fastest: Manual groupBy (2.5x faster)

View exact numbers

✓ Manual groupBy: 8,951,643 ops/sec
• Object.groupBy: 3,581,509 ops/sec

Results show median performance across all community submissions. Run this benchmark yourself to verify on your device.

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.groupBy
Manual groupBy

Fastest: N/A

Slowest: N/A

Latest run results:

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

User agent: Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Mobile Safari/537.36

Browser/OS: Chrome Mobile 138 on Android

View result in a separate tab

Manual groupBy

9.0M/s

Object.groupBy

3.8M/s

View exact numbers

Test name	Executions per second
✓ Manual groupBy	8,999,024 Ops/sec
Object.groupBy	3,796,548 Ops/sec

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, compared, and their pros and cons.

**What is being tested?**

The benchmark compares two approaches to group data by occupation using either the `Object.groupBy()` method or a custom implementation called `groupBy()`. The test case is designed to measure the performance of each approach on a sample dataset containing 6 objects with varying ages and occupations.

**Options compared:**

1. **`Object.groupBy()`**: This method uses the built-in `groupBy()` function from the JavaScript Object prototype.
2. **Custom implementation (`groupBy()`)**: A custom function that takes an array and a mapper function as arguments, which is used to group the data by occupation.

**Pros and Cons of each approach:**

1. **`Object.groupBy()`**:
	* Pros:
		+ Built-in method, so it's well-supported across browsers.
		+ Simplifies code, as it doesn't require manual looping or recursion.
	* Cons:
		+ Might be slower due to the overhead of calling a built-in function.
		+ May not be suitable for all use cases, as its behavior is specific to the Object prototype.
2. **Custom implementation (`groupBy()`)**:
	* Pros:
		+ Allows for more control over the grouping logic and performance optimization.
		+ Can be optimized for specific use cases or data structures.
	* Cons:
		+ Requires manual looping or recursion, which can increase code complexity.
		+ May not be supported across all browsers, especially older ones.

**Library:**

The `groupBy()` function used in the custom implementation is a built-in JavaScript method that groups an array of objects by a specified key (in this case, occupation). It's a simple and efficient way to perform data aggregation.

**Special JS feature or syntax:**

None mentioned in this benchmark. However, it's worth noting that `Object.groupBy()` relies on the `map` function, which is a standard JavaScript method for creating new arrays by applying a transformation function to each element of an existing array.

**Alternative approaches:**

1. **Using `reduce()`**: Instead of using `groupBy()`, you could use the `reduce()` function to achieve similar results.
2. **Using a library like Lodash**: The `groupBy()` function is also available in the popular Lodash library, which provides a more comprehensive set of utility functions for JavaScript development.

In summary, the benchmark compares two approaches to group data by occupation: using the built-in `Object.groupBy()` method versus a custom implementation. The choice between these approaches depends on the specific use case and performance requirements.

Object.groupBy vs manual groupBy (version: 0)

Comparing performance of: `Object.groupBy vs Manual groupBy`

Created: one year ago by: Registered User

Go to the latest result

Object.groupBy

Manual groupBy

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Object.groupBy vs manual groupBy (version: 0)

Comparing performance of: Object.groupBy vs Manual groupBy

Created: one year ago by: Registered User

Go to the latest result

Object.groupBy

Manual groupBy

Historical Performance Data aggregated from 6 community runs

Desktop Results:

Chrome 6 runs

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

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

Related benchmarks

Comparing performance of: `Object.groupBy vs Manual groupBy`