Fixing the Function Not Defined Error in Phaser 3 NPC Class Implementation

Discover how to solve the common error of methods not being defined in Phaser 3 when dealing with custom classes. Learn step-by-step how to correct your game logic for smooth operations.
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Fixing the Function Not Defined Error in Phaser 3 NPC Class Implementation

Creating games using the Phaser 3 framework can be a rewarding yet challenging experience. One common issue that developers face, especially when dealing with custom classes, is the error message indicating that a function does not exist or is not defined. This guide walks you through a real-world example of this error using an NPC class and provides a structured solution to help you overcome it.

The Problem: Understanding the Error

You have a custom NPC class that contains a method called chase. Here's an overview of the situation:

In contrast, another method, updateMe, works perfectly fine.

To clarify, here's the relevant code snippet from your NPC class:

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

And the calling part in the update function looks like this:

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

Investigating the Error

The Solution: Modifying the Group Creation

To solve this problem, you simply need to ensure that the NPCs are created as instances of your custom class rather than as generic sprites. This is achieved by altering the way you define the group in your code:

Step-by-Step Solution

Locate this line of code that creates the NPC group:

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

Update it to include the classType parameter, specifying your custom NPC class like this:

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

With this change, your NPCs will now be instantiated properly as instances of your custom class. As a result, they will have access to all the methods you’ve defined, such as chase.

Additional Implementation Example

Here’s a brief demonstration of how these changes might look in a simple game configuration:

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

Conclusion

By ensuring your game objects are created as instances of custom classes, you can avoid common pitfalls like encountering undefined functions. The key takeaway is to always specify the classType when creating groups of custom objects in Phaser 3.

With these adjustments, your NPCs should now function correctly within your game, allowing you to maintain smooth gameplay and robust interactions.

Happy coding, and may your game development journey continue smoothly!