How to Resolve Vaadin 23 JavaScript Import Issues for Custom Components

Discover solutions to the `Uncaught ReferenceError` issue in Vaadin 23 when importing JavaScript files for custom components. Enhance your development experience with proper imports.
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Fixing JavaScript Import Issues in Vaadin 23

Building web applications using Vaadin can be a rewarding experience, but sometimes developers encounter hurdles, especially when integrating JavaScript functionalities. One common issue faced by many is the importation of JavaScript files, which leads to errors in the console, potentially disrupting seamless user experience. In this post, we’ll explore a specific case involving a cookie warning popup and how to rectify JavaScript import problems in Vaadin 23.

The Problem: Uncaught ReferenceError

When attempting to execute a JavaScript function in response to a button click, you might encounter an error similar to this in your browser console: "Uncaught ReferenceError: fadeOut is not defined". This can indicate that the function is either not being loaded correctly or is not recognized in the current scope.

Context of the Issue

In your implementation, you have a class named CookiesDiv that extends the Vaadin Div class, presenting a cookie warning popup. This popup should call a JavaScript function, fadeOut, when the user clicks the "GOT IT" button. However, despite having the JavaScript file imported, the function is reported as undefined.

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

Despite changing the fadeOut function in your JS code to be a part of the window object, you're still facing issues with the function being recognized.

Solution: Correct Your Imports

To resolve this issue, you need to ensure the paths to your CSS and JavaScript files are accurate. Below are the updated import statements that resolve the problem:

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

Explanation of the Changes

Relative Paths: The ./ indicates that the paths are relative to where the current Java class is located. Using this notation ensures that Vaadin knows exactly where to find your JavaScript and CSS files.

Additional Considerations

CSS Properties Ignored

You mentioned that some CSS properties are ignored in your project. This can often arise from:

Incorrect Path: Ensure your CSS file is effectively linked and correctly referenced.

Specificity Issues: If another CSS rule is more specific, it may take precedence over yours. Use your browser's developer tools to inspect elements and check CSS rules applied.

Testing

Once you have modified the import statements, and ensured the paths are correct, rebuild your Vaadin application and test the behavior of the button. The error should now be resolved, allowing the fadeOut functionality to execute as intended.

Conclusion

When working with Vaadin 23, ensure that the imports for JavaScript and CSS files are properly specified, using the correct relative paths. This simple change can significantly enhance your application’s functionality and resolve common issues like the ReferenceError. Continue to explore and test your components thoroughly, and enjoy the rapid development experience Vaadin offers!