Let's break down the provided benchmark and explain what is being tested.

Benchmark Overview

The benchmark compares two approaches to iterate over an object in JavaScript: Object.entries and Object.keys. The test case creates an object with 100 keys (unique identifiers) and values, generated randomly using a custom function makeid(). The goal is to determine which approach is faster for this specific use case.

Options Compared

Two options are being compared:

1. Object.entries(): This method returns an array of key-value pairs in the object, where each pair is an array with two elements: the key and the value.
2. Object.keys(): This method returns an array of strings representing the keys of the object.

Pros and Cons

Here's a brief overview of each approach:

• Object.entries():
  • Pros:
    • Directly returns an array of key-value pairs, making it easier to process.
    • Can be faster when working with objects where you need both key and value.
  • Cons:
    • Returns an array of arrays (each element is an array), which can lead to unnecessary overhead.
• Object.keys():
  • Pros:
    • Returns a simple array of strings, making it easier to iterate over the keys.
    • Less memory-intensive than Object.entries().
  • Cons:
    • Requires additional processing to access the corresponding values.

Library and Purpose

In this benchmark, no libraries are explicitly used. However, window.parentObj is a custom object created in the script preparation code. Its purpose is to serve as a test subject for iterating over its key-value pairs using both Object.entries() and Object.keys() methods.

Special JS Feature or Syntax (None)

There are no special JavaScript features or syntax used in this benchmark.

Alternative Approaches

If you need to iterate over an object's keys, other approaches might include:

• Using a for...in loop: for (var key in obj) { ... }
• Using a for...of loop with Object iterators: for (const [key, value] of Object.entries(obj)) { ... } (not used in this benchmark)
• Using a library like Lodash's keys() function: _object.keys()

Keep in mind that the choice of approach depends on your specific use case and performance requirements.

Benchmark Preparation Code Explanation

The script preparation code creates an object with 100 random keys and values, assigns it to window.parentObj, and then iterates over its key-value pairs using both Object.entries() and Object.keys() methods. The resulting benchmark data is stored in the RawUAString property of each test case.

Latest Benchmark Result Explanation

The latest benchmark result shows the execution per second for each browser (in this case, only Firefox 102) on a Linux desktop system. The values indicate that Object.entries() outperforms Object.keys(), with approximately 2.5 times more executions per second.