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

What is being tested?

The provided JSON represents a JavaScript microbenchmark that compares two approaches to formatting numbers: Intl.NumberFormat (new) and an existing implementation (assuming this is a custom or legacy code).

Options compared:

1. New NumberFormat (Intl.NumberFormat): This approach uses the Internationalization API, which provides a standardized way to format numbers according to the user's locale settings.
2. Existing NumberFormat: This is likely a custom or legacy implementation that may not follow standard guidelines or best practices.

Pros and Cons of each approach:

1. Intl.NumberFormat (New):
   • Pros:
     • Follows internationalization standards, ensuring accurate formatting for different locales.
     • Provides a standardized way to format numbers, making it easier to maintain and update code.
     • Often more efficient and concise than custom implementations.
   • Cons:
     • May require additional setup or configuration to work properly.
     • Can be slower due to the overhead of internationalization processing.
2. Existing NumberFormat:
   • Pros:
     • May be faster due to reduced overhead from internationalization processing.
     • Can be more familiar and easier to maintain for developers who already know the custom implementation.
   • Cons:
     • Lacks standardization, making it harder to maintain and update code across different locales.
     • May not provide accurate formatting for all locale settings.

Library:

The Intl.NumberFormat library is a part of the JavaScript API, specifically designed for internationalization. It provides a standardized way to format numbers according to the user's locale settings.

Special JS feature or syntax:

There isn't any explicit mention of special JavaScript features or syntax in this benchmark. However, the use of Intl.NumberFormat does rely on some language-specific features and APIs that may not be widely supported across all browsers or environments.

Other alternatives:

If you're looking for alternative approaches to formatting numbers, you might consider:

1. Number formatting libraries: There are many third-party libraries available that provide number formatting capabilities, such as moment.js, numeral.js, or custom solutions like jQuery NumberFormatter.
2. Locale-specific formatting functions: Depending on your specific use case, you might need to rely on locale-specific formatting functions provided by the browser's API (e.g., navigator.language) or a library like i18n.js.

Keep in mind that each approach has its pros and cons, and the best choice ultimately depends on your project's requirements, performance constraints, and development team's expertise.