Let's dive into the world of JavaScript microbenchmarks!

The provided JSON represents a benchmark test for two approaches to retrieving property names and descriptors from an object: getOwnPropertyNames and getOwnPropertyDescriptors.

What is being tested?

These tests compare the performance of two methods:

1. getOwnPropertyNames: This method returns an array of strings representing the names of properties defined directly on the given object. It does not include inherited properties.
2. getOwnPropertyDescriptors: This method returns an object containing the descriptors of all properties defined directly and indirectly on the given object.

Options compared

The two options being compared are:

1. Object.getOwnPropertyNames(): Returns an array of strings representing the names of properties defined directly on the object.
2. Object.getOwnPropertyDescriptors(): Returns an object containing the descriptors of all properties defined directly and indirectly on the object.

Pros and Cons:

• getOwnPropertyNames(): Pros:
  • Faster, as it only iterates over the object's own properties.
  • Less memory-intensive, as it doesn't store property descriptors.
• Cons:
  • Does not include inherited properties in its results.
  • May not be suitable for objects with a large number of properties or complex inheritance hierarchies.
• getOwnPropertyDescriptors(): Pros:
  • Includes all properties, including inherited ones.
  • Can provide more information about each property (e.g., value type, accessibility).
• Cons:
  • Slower, as it needs to access the object's prototype chain and iterate over its properties.
  • More memory-intensive, as it stores property descriptors.

Library: None

There are no external libraries used in these tests. The Object object is a built-in JavaScript object that provides various methods for manipulating objects, including the two options being compared.

Special JS feature or syntax: None

The tests use only standard JavaScript features and syntax.

Benchmark preparation code

The provided benchmark preparation code defines a simple function objectProperties that takes an object and returns a result object containing property names. The function uses Object.getPrototypeOf to traverse the object's prototype chain and iterates over its properties using Object.getOwnPropertyNames (or Object.getOwnPropertyDescriptors) to retrieve their names.

Individual test cases

There are two individual test cases:

1. getOwnPropertyNames: This test case runs the objectProperties function with a new instance of MediaSource object, passing Object.getOwnPropertyNames as the method to use.
2. getOwnPropertyDescriptors: This test case is similar to the first one, but uses Object.getOwnPropertyDescriptors instead.

Latest benchmark result

The provided JSON contains two execution results:

1. The first result shows a faster execution time for getOwnPropertyNames, with 183718 executions per second.
2. The second result shows a slower execution time for getOwnPropertyDescriptors, with 90338 executions per second.

Alternatives

Other alternatives for retrieving property names and descriptors include:

• Using Reflect.ownKeys() or Object.keys() to get an array of property names, which may be more efficient than using Object.getOwnPropertyNames().
• Using Object.entries() to get an array of key-value pairs, where each pair contains the name and descriptor of a property.
• Implementing custom methods using iterators or other advanced JavaScript features.