Understanding JavaScript getter and setter Functions: Enumerating Properties the Right Way

Learn how to effectively enumerate properties defined as getter and setter functions in JavaScript classes. Discover the solutions to test and list these special kinds of properties with clear examples.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Can I enumerate properties that only exist as getter/setter functions?

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Understanding JavaScript getter and setter Functions: Enumerating Properties the Right Way

In JavaScript, classes can have getter and setter functions that manage how properties are accessed and changed. However, it can be confusing when you try to determine their existence or list them as properties. If you've ever wondered, "Can I enumerate properties that only exist as getter/setter functions?", you're not alone! This guide will break down how to test for these unique properties and list them effectively.

The Challenge: Listing getters and setters

Let’s consider a simple class that uses getter and setter functions:

[[See Video to Reveal this Text or Code Snippet]]

In this example, when you check for the property b using hasOwnProperty, it returns false. This might be perplexing since you want to know if the property exists. The crux of the matter is that getter and setter functions are not part of the instance itself; instead, they live on the prototype.

The Solution: Checking from the Prototype

To determine the presence of getter and setter functions, you need to call hasOwnProperty on the prototype, not the instance. Here's how to effectively handle this situation:

Step 1: Access the Prototype

[[See Video to Reveal this Text or Code Snippet]]

[[See Video to Reveal this Text or Code Snippet]]

Summary of the Approach

List All getters and setters:

Filter for properties that are getters or setters (i.e., those without a value property).

By following these steps, you can effectively list and verify the existence of getter and setter properties in your JavaScript classes.

Conclusion

Feel free to experiment with your own classes using these techniques and discover how JavaScript handles properties behind the scenes. Happy coding!