Benchmark: Lodash keyBy vs JS Map

Script Preparation code:

window.data = [];
for (let i = 0; i < 10000; i++) {
    data.push({
        key: `key${i}`
    });
}

window.dataBig = [];
for (let i = 0; i < 100000; i++) {
    dataBig.push({
        key: `key${i}`
    });
}

Tests:

Lodash keyBy (10k entries)
const keyed = _.keyBy(data, 'key')
JS Map (10k entries)
const map = new Map(data.map((r, i) => [data.key, i]));
Lodash keyBy (100k entries)
const keyed = _.keyBy(dataBig, 'key')
JS Map (100k entries)
const map = new Map(dataBig.map((r, i) => [dataBig.key, i]));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Lodash keyBy (10k entries)
JS Map (10k entries)
Lodash keyBy (100k entries)
JS Map (100k entries)

Fastest: N/A

Slowest: N/A

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

LLMs can make mistakes. Check important info.

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

**Benchmark Definition**

The benchmark is testing two approaches for creating an index of objects by their key:

1. Using Lodash's `keyBy` function
2. Creating a JavaScript `Map` data structure manually

**Script Preparation Code**

The script preparation code creates two arrays, `data` and `dataBig`, each containing 10,000 and 100,000 objects respectively, with a single property "key" that is used to create the index.

**Html Preparation Code**

There is no HTML preparation code provided, which suggests that this benchmark is focused on measuring the performance of JavaScript engines in a headless environment.

**Individual Test Cases**

The benchmark consists of four test cases:

1. **Lodash keyBy (10k entries)**: This test case uses Lodash's `keyBy` function to create an index of objects by their "key" property.
2. **JS Map (10k entries)**: This test case creates a JavaScript `Map` data structure manually to achieve the same result as Lodash's `keyBy`.
3. **Lodash keyBy (100k entries)**: Similar to the first test case, but with 100,000 entries in the `dataBig` array.
4. **JS Map (100k entries)**: The second manual approach is repeated for a larger dataset.

**Options Compared**

The two main approaches being compared are:

* Lodash's `keyBy` function
* Creating a JavaScript `Map` data structure manually

**Pros and Cons of Each Approach**

* **Lodash's `keyBy` function**:
	+ Pros: Easy to use, efficient, and well-tested.
	+ Cons: Requires an external library (Lodash).
* **Creating a JavaScript `Map` data structure manually**:
	+ Pros: No external dependencies, can be more flexible.
	+ Cons: More verbose and error-prone than using Lodash's `keyBy`.

**Library Used**

In this case, the Lodash library is used for its `keyBy` function. Lodash is a popular utility library that provides a set of functional programming helpers, including data manipulation functions like `keyBy`.

**Special JS Feature or Syntax**

There are no specific JavaScript features or syntax being tested in this benchmark.

**Other Considerations**

When choosing between these two approaches, consider the following factors:

* Performance: Lodash's `keyBy` is likely to be faster due to its optimized implementation.
* Readability: Manual `Map` creation can be more verbose and harder to read than using Lodash's `keyBy`.
* Maintainability: Using an external library like Lodash can make your codebase more maintainable, as the library will handle the underlying implementation details.

**Alternatives**

If you don't want to use Lodash or a similar utility library, you could consider alternative approaches, such as:

* Using the `reduce` method with an accumulator object
* Utilizing the `Map` constructor with a callback function
* Implementing your own indexing algorithm using JavaScript arrays and loops.

However, these alternatives may not be as efficient or readable as using Lodash's `keyBy` function.

Latest run results:

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

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/126.0.0.0 Safari/537.36

Browser/OS: Chrome 126 on Windows

View result in a separate tab

Test name	Executions per second
Lodash keyBy (10k entries)	1323.8 Ops/sec
JS Map (10k entries)	704.3 Ops/sec
Lodash keyBy (100k entries)	71.6 Ops/sec
JS Map (100k entries)	60.5 Ops/sec

Related benchmarks:

Lodash keyBy vs JS Map (version: 0)

Comparing performance of: Lodash keyBy (10k entries) vs JS Map (10k entries) vs Lodash keyBy (100k entries) vs JS Map (100k entries)

Created: 5 months ago by: Guest

Jump to the latest result

Lodash keyBy (10k entries)

JS Map (10k entries)

Lodash keyBy (100k entries)

JS Map (100k entries)

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A

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