Benchmark: flatMap vs reduce (0302)

Script Preparation code:

var agency = {
 'sellerName': 'test' 
};
var agencyObj = {
 'sellerName': 'abc' 
};

Tests:

reduce
var agencyItems = Object.keys(agency).reduce((acc, key) => { const value = agencyObj?.[key] if (value) { acc.push({ title: agency[key], value, }) } return acc }, [])
flatMap
var agencyItems = Object.keys(agency).flatMap((key) => { const value = agencyObj?.[key] return value ? { title: agency[key], value } : [] })

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
reduce
flatMap

Fastest: N/A

Slowest: N/A

Latest run results:

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

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I'd be happy to help explain the JavaScript microbenchmark on MeasureThat.net.

**Overview**

The benchmark compares the performance of two approaches: `reduce` and `flatMap` when processing an array of key-value pairs from two objects, `agency` and `agencyObj`. The test case aims to determine which approach is more efficient in terms of execution speed.

**Options Compared**

The two options being compared are:

1. **Reduce**: This method reduces an array of values to a single value. In this case, it's used to process the key-value pairs from both objects and create an array of objects with `title` and `value` properties.
2. **FlatMap**: This method returns a new array created by applying a provided function to each element in an array.

**Pros and Cons**

* **Reduce**:
	+ Pros: Can be more memory-efficient if the resulting array is not needed, as it only iterates over the keys once.
	+ Cons: May have higher overhead due to the need to accumulate values in the accumulator.
* **FlatMap**:
	+ Pros: More intuitive and easier to read for developers familiar with functional programming concepts. It also avoids the accumulation problem associated with `reduce`.
	+ Cons: May be less memory-efficient if the resulting array is needed, as it iterates over the keys twice.

**Library/Functionality**

Neither of the two options relies on a specific library or functionality beyond standard JavaScript. However, it's worth noting that the use of optional chaining (`?.`) in the `flatMap` implementation is a modern JavaScript feature introduced in ECMAScript 2020. If you're targeting older browsers or environments, you may need to replace this with a more compatible approach.

**Special JS Feature/Syntax**

The use of arrow functions and template literals (e.g., `${}`) is a modern JavaScript syntax that's widely supported across most browsers. However, if you're targeting older environments, you may need to use alternative syntax or transpile your code using a tool like Babel.

**Other Alternatives**

If you wanted to explore other approaches, here are some alternatives:

* **forEach**: You could use `forEach` instead of `reduce` or `flatMap`, which would involve iterating over the keys and objects in separate loops.
* **For...of loop**: Another alternative is using a traditional `for...of` loop with an iterator, which would also involve iterating over the keys and objects.

In summary, both `reduce` and `flatMap` can be effective approaches for processing key-value pairs from multiple objects. However, `reduce` might have higher overhead due to accumulation, while `flatMap` is more intuitive but may consume more memory if needed.

Related benchmarks:

flatMap vs reduce (0302) (version: 0)

Comparing performance of: reduce vs flatMap

Created: 3 years ago by: Guest

Jump to the latest result

reduce

flatMap

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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