Let's break down the benchmark and its test cases.

What is being tested?

The benchmark is designed to compare three approaches for iterating over an object's properties:

1. Object.getOwnPropertyNames(): This method returns an array of strings representing the names of all properties (including inherited ones) that are directly accessible on an object.
2. Cached property names: In this approach, we assume that some libraries or frameworks provide a cached list of property names for an object, which is then used to iterate over the properties.
3. for...in loop with filtering: This approach uses the for...in loop to iterate over all properties of an object and skips any properties whose name starts with a dollar sign ($).

Options comparison

The three approaches have different pros and cons:

• Object.getOwnPropertyNames():
  • Pros: Simple, straightforward, and efficient.
  • Cons: May include inherited properties, which can be slow to iterate over for large objects.
• Cached property names:
  • Pros: Can be faster than getOwnPropertyNames() if the cached list is already available.
  • Cons: Assumes that a library or framework provides the cached list, which may not always be the case.
  • Pros (if implemented correctly): Avoids iterating over inherited properties and can be optimized for large objects.
  • Cons (if implemented incorrectly): May still include inherited properties or introduce additional overhead.
• for...in loop with filtering:
  • Pros: Flexible, as it allows filtering out properties based on their names.
  • Cons: Can be slower than getOwnPropertyNames() and cached property names if not optimized.

The for...in loop approach is currently the fastest, but this might change depending on the specific implementation and browser optimizations.

Library considerations

The benchmark uses the Object.getOwnPropertyNames() method, which is a standard JavaScript method. No external libraries are required for these test cases.

Special JS features or syntax

There are no special JavaScript features or syntax used in these test cases.

Other alternatives

If you wanted to include other approaches in your benchmark, some alternative methods for iterating over an object's properties could be:

• Using Object.keys() (which returns only own enumerable properties) and then filtering out properties whose names start with a dollar sign.
• Using a custom iteration function or a recursive approach.
• Comparing performance of using for...in, for...of (if supported), or other iteration methods.

Keep in mind that each alternative method has its pros and cons, and the best choice depends on your specific use case and requirements.