Let's break down what's being tested in this benchmark.

Benchmark Overview

The benchmark is comparing three different approaches to check if a variable foo is undefined/unexistent:

1. Using Lodash's isUndefined() function
2. Using the native JavaScript operator === undefined
3. Simplifying the native JavaScript approach using the ! operator

Options Compared

We have three options being compared:

• Lodash.isUndefined(): This uses the lodash.isUndefined() function, which is a utility function from the Lodash library. It returns true if the given value is undefined.
• Native js === undefined: This uses the native JavaScript operator === undefined to check if the variable foo is undefined. The === operator checks for exact equality between two values, and in this case, it's being used to compare with the undefined keyword.
• Simplify native js !foo: This simplifies the native JavaScript approach by using the ! operator to negate the value of foo. If foo is falsey (i.e., it's null, undefined, 0, an empty string, etc.), this expression will evaluate to true. Otherwise, it will evaluate to false.

Pros and Cons

• Lodash.isUndefined(): This approach provides a more explicit and readable way of checking if a value is undefined. However, it comes with a performance cost since it involves calling a function from the Lodash library.
  • Pros: More explicit and readable
  • Cons: Performance overhead due to library call
• Native js === undefined: This approach is simple and lightweight, but it's also more prone to errors if not used correctly. The === operator can be confused with other comparisons, making it harder to read.
  • Pros: Lightweight and simple
  • Cons: Prone to errors and less readable
• Simplify native js !foo: This approach is a good compromise between the two. It's lightweight and easy to understand, but still provides some readability benefits by using a clear operator (!).
  • Pros: Balanced performance and readability
  • Cons: May require additional mental processing to understand the operator's meaning

Library and Special JS Feature

The benchmark uses Lodash, which is a popular utility library for JavaScript. It provides various functions for tasks like string manipulation, array operations, and more.

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

Alternatives

Other alternatives to check if a variable is undefined/unexistent include:

• Using typeof with the undefined keyword: typeof foo === 'undefined'
• Using the || operator with an empty string: `foo || ''
• Using the in operator with undefined: foo in undefined

However, these alternatives are not tested in this benchmark.

Conclusion

In conclusion, this benchmark is testing three different approaches to check if a variable is undefined/unexistent: using Lodash's isUndefined() function, native JavaScript's === undefined operator, and simplifying the native approach with the ! operator. The pros and cons of each approach are discussed, highlighting the trade-offs between readability, performance, and simplicity.