The benchmark tests three different methods for converting the values of a Map object to an array in JavaScript. The objective is to compare their performance, particularly focusing on execution speed, as measured in executions per second. Here’s a detailed breakdown of the comparison:

Options Compared

1. Map.values().toArray()

   • Description: This method attempts to call a hypothetical toArray() function directly on the iterator returned by Map.values(). However, toArray() is not a native method in the JavaScript language for iterators.
   • Pros: Theoretically, this syntax could be cleaner if a toArray() method existed, allowing for method chaining.
   • Cons: Since toArray() does not exist on the Map.values() iterator, this will likely result in a runtime error. Therefore, this option effectively tests the invalidity of using a non-existent method.

2. Array.from(Map.values())

   • Description: This method leverages the Array.from() static method, which creates a new array from an iterable (in this case, the values of a Map).
   • Pros:
     • This is a standard way to convert an iterable (like the Map.values() iterator) into an array.
     • It’s concise and easy to read.
     • Supports additional transformation and mapping functions as part of its API.
   • Cons: Slightly more overhead compared to spread syntax for very large data sets, since it has to create a new array and populate it.

3. [...Map.values()]

   • Description: This utilizes the spread syntax (...) to expand the iterable returned by Map.values() into an array.
   • Pros:
     • Concise and expressive, making use of modern JavaScript syntax.
     • Typically fast for converting iterables into arrays, as it doesn’t require an intermediary function call.
   • Cons: Not as flexible as Array.from() for transformations, though in many cases where no transformation is needed, it’s very efficient.

Benchmark Results

From the benchmark results, we can see the following performance measurements (in executions per second):

• Array.from(Map.values()): ~39,053
• [...Map.values()]: ~38,988
• Map.values().toArray(): ~6,268 (likely not representative due to the incorrect assumption about a non-existent method).

Conclusion and Considerations

• The best performers are Array.from() and the spread syntax, which showcase similar performance metrics, with a slight edge going to Array.from().
• The Map.values().toArray() test serves as a cautionary example, affirming that invalid method calls can lead to performance measurements that fail to represent a valid use case in a project.

Alternatives

• Other alternatives for converting Map values to an array include:
  • Using a loop (e.g., forEach): Can be used when additional processing is required during the conversion.
  • Using map() on the iterator: This would need to first convert the values to an array using one of the valid methods above before applying map().

When deciding which method to use, developers should balance performance with code readability and maintainability, along with the specific context of the application.