Benchmark: MapFIlter vs. Reduce

Script Preparation code:

window.largeArr = [];
for(i=0; i<1000000; i++){
  window.largeArr.push([i.toString(), i])
  if (Math.random() < 0.1) window.largeArr.push([undefined, i])
}

Tests:

MapFilter
window.largeArr.map(el => el[0]).filter(Boolean)
Reduce
window.largeArr.reduce((all, el) => { if (el[0]) { all.push(el[0]); } return all; }, [])

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
MapFilter
Reduce

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 benchmark JSON and explain what's being tested, compared, and other considerations.

**Benchmark Overview**

The benchmark compares two approaches to process an array of data: `map` vs. `reduce`. The input data is generated by creating an array `window.largeArr` with 1 million elements each containing a string value and an index. Some elements have a random chance (10%) of having `undefined` as the first element.

**Options Compared**

The two options being compared are:

1. **Map**: `window.largeArr.map(el => el[0]).filter(Boolean)`
	* Purpose: Create a new array with only the first element of each object in the original array.
2. **Reduce**: `window.largeArr.reduce((all, el) => {\r\n\tif (el[0]) {\r\n      \tall.push(el[0]);\r\n    }\r\n  \treturn all;\r\n}, [])`
	* Purpose: Accumulate only the first element of each object in the original array into a new array.

**Pros and Cons**

Here's a brief summary of the pros and cons of each approach:

* **Map**:
	+ Pros: Easy to read and maintain, concise syntax.
	+ Cons: Creates a new array, which can lead to memory allocation and deallocation overhead. Filter() is also called for each element in the original array.
* **Reduce**:
	+ Pros: More efficient use of memory (no array creation), accumulates values incrementally.
	+ Cons: Requires understanding of accumulator pattern, more complex syntax.

**Library**

In this benchmark, `filter(Boolean)` is used as a library. This is a shorthand for calling `Array.prototype.filter()` and returning only the elements that are truthy. It's a utility function that simplifies the code without altering its behavior.

**Special JavaScript Feature or Syntax**

The benchmark uses the `=>` operator (also known as an arrow function) in the `map` option, which is a shorthand for creating functions without declaring them with `function`. This syntax was introduced in ECMAScript 2015 (ES6).

**Other Considerations**

* The benchmark measures the performance of each approach on a large input dataset to compare their relative efficiency.
* The use of `window.largeArr` suggests that this benchmark is focused on comparing the performance of JavaScript engines, rather than other factors like CPU or memory usage.
* The absence of any caching or optimization in the benchmark code ensures that the results are representative of typical usage scenarios.

**Other Alternatives**

If you're looking for alternatives to these approaches, consider:

1. **For...of Loop**: Instead of using `map` or `reduce`, you could use a traditional `for...of` loop with an array iterator.
2. **Array.prototype.forEach()`: Similar to the `for...of` loop approach, but uses a more concise syntax.
3. **Other libraries or frameworks**: Depending on your specific requirements, you might consider using specialized libraries like Lodash or Ramda for array manipulation, which can provide optimized implementations of common operations.

I hope this explanation helps you understand what's being tested in the provided benchmark!

Latest run results:

Run details: (Test run date: 4 years ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/81.0.4044.122 Safari/537.36

Browser/OS: Chrome 81 on Linux

View result in a separate tab

Test name	Executions per second
MapFilter	14.9 Ops/sec
Reduce	9.4 Ops/sec

Related benchmarks:

MapFIlter vs. Reduce (version: 0)

Comparing performance of: MapFilter vs Reduce

Created: 4 years ago by: Guest

Jump to the latest result

MapFilter

Reduce

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):