Benchmark Overview

MeasureThat.net is a website that allows users to create and run JavaScript microbenchmarks. The benchmark in question involves measuring the performance of three different approaches for filtering an array or map.

Benchmark Definition JSON

The benchmark definition JSON provides the following information:

• "Name": A unique identifier for the benchmark.
• "Description": An optional description of the benchmark, which is empty in this case.
• "Script Preparation Code": A JavaScript code snippet that prepares the data and variables used by the benchmark. In this case, it creates an array and a map from 0 to 999 using Array.from and Map.
• "Html Preparation Code": An optional HTML code snippet for preparing the HTML environment for the benchmark, which is empty in this case.

Test Cases

The test cases are defined as an array of objects, each representing a single test. The test case definition includes:

• "Benchmark Definition": A JavaScript code snippet that defines the specific operation to be measured.
• "Test Name": A unique identifier for the test case.

There are three test cases:

1. "iterate on map with values() and filter":
   • Uses the values() method of the Map object to iterate over its entries, and filters out odd numbers using an array method (push).
2. "iterate on map with forEach() and filter":
   • Uses the forEach() method of the Map object to iterate over its entries, and filters out odd numbers using an array method (push).
3. "iterate on array and filter":
   • Directly uses the filter() method of the Array object to filter out odd numbers.

Comparison

The three test cases compare different approaches for filtering arrays or maps:

• Iterating over a Map object using values(), then filtering with an array method (push).
• Iterating over a Map object using forEach(), then filtering with an array method (push).
• Directly using the filter() method of the Array object.

Pros and Cons

Here's a brief analysis of each approach:

1. Iterate over Map using values(), filter: This approach is more verbose but provides better control over iteration order (stable). However, it may not be as efficient due to the extra array method call.
2. Iterate over Map using forEach(), filter: This approach uses a callback function for filtering, which can lead to potential issues with scope and closure management. However, it's often more concise than using values() and an additional array method.
3. Directly use filter() on Array object: This approach is likely the most efficient as it only involves a single method call.

In terms of performance, the filter() method is generally the fastest option. The forEach() method with filtering can be slower due to the overhead of iterating over each element using a callback function. Iterating over a Map object using values() and an additional array method can be slower as well, but the difference is likely minimal.

Alternative Approaches

Other approaches to filter arrays or maps include:

• Using map() with a callback function (e.g., map(o => o % 2 === 0)).
• Using reduce() with an accumulator and callback function.
• Using specialized libraries like Lodash (_.filter()) or Ramda (R.filter()).

Keep in mind that each approach has its own trade-offs between conciseness, readability, and performance.

Special JavaScript Features or Syntax

This benchmark does not use any special JavaScript features or syntax beyond the standard language.