Let's break down what's being tested in this JavaScript microbenchmark on MeasureThat.net.

Benchmark Definition

The benchmark compares two approaches to delete or set a property to undefined on an object:

1. Delete: delete obj.property
2. Undefined: obj.property = undefined;

Options Compared

We have two options being compared:

• delete keyword: This is a built-in JavaScript operator that removes a property from an object by its name.
• Assignment to undefined: Setting a property to undefined effectively deletes it.

Pros and Cons of Each Approach

1. Delete
   • Pros:
     • More concise and readable syntax.
     • Often perceived as more efficient since it doesn't create a temporary variable.
   • Cons:
     • Can be slower due to the dynamic nature of JavaScript's property removal process.
     • May not work consistently across all browsers and environments.
2. Undefined
   • Pros:
     • More explicit and predictable behavior.
     • Works consistently across all browsers and environments.
   • Cons:
     • Requires an additional assignment statement, which can be less concise.

Other Considerations

• Memory Management: Both approaches may have implications for memory management, as the delete keyword only removes a reference to the property from the object's internal hash table, while setting a property to undefined actually deallocates the memory allocated by the property.
• Property Existence Checks: Depending on use cases, it might be necessary to check if a property exists before attempting to delete or set it to undefined. Both approaches can lead to additional checks.

Library or Special JS Feature Used

There are no libraries mentioned in this benchmark, and no special JavaScript features (e.g., async/await, generators) are used beyond the standard JavaScript language.

Alternatives

Other alternatives for deleting properties from an object include:

• Object.defineProperty() with configurable: false
• Object.delete() (not supported in older browsers)
• Using a temporary variable and assigning it to null or undefined, followed by property removal

Keep in mind that these alternatives might not offer significant performance benefits over the delete and assignment approaches, and may have different implications for memory management and other factors.