Fixing Nested Custom Elements Not Showing Data in JavaScript

Discover how to resolve issues with `nested custom elements` not displaying data correctly in your JavaScript projects by implementing simple fixes and best practices.
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Fixing Nested Custom Elements Not Showing Data in JavaScript

When developing web applications, particularly those that utilize custom elements, you may encounter issues where your data does not display as expected. This is a common problem faced by many developers working with web components. In this post, we'll explore a scenario where a developer tries to display a list of movies using a custom element but ends up with a blank display. Let’s dive into the issue and its solution to enhance your JavaScript skills!

The Problem

In the context of a movie-listing web application, the developer created a custom HTML element called <movie-container> to encapsulate the features for displaying movies fetched from the themoviedb API. The problem arises when the movie items do not appear on the web page even though the <movie-container> itself is rendered correctly, showing -shadow-root (open) in inspection tools.

Here is a brief summary of the code that caused the issue:

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

The developer forgot to call the render method in the setter function, which is critical for displaying the list of movies. Let’s look at how to correct this problem and ensure that custom elements function as intended.

The Solution

Step 1: Calling the Render Method Correctly

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

Step 2: Utilizing the :host Pseudo-Class Correctly

After ensuring that the render method is called, there’s another important aspect to check concerning the CSS styles. When using the :host pseudo-class in the shadow DOM, ensure that your selectors are written correctly. For instance, if you want an effect when hovering over your custom element, the current code might look like this:

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

This code should be updated to use the correct format for the :host pseudo-class function. Here’s the adjusted line:

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

Conclusion

By implementing these two changes—ensuring the render method is executed and correcting the CSS pseudo-class—you can successfully display your nested custom elements. This approach not only fixes the immediate problem but also helps you follow best practices in your development:

Call methods correctly: Ensure your methods are called (with parentheses) to execute their functionality.

Write CSS selectors correctly: Use the :host() function to effectively manage styles within shadow DOMs.

With these fixes in place, your movie-container should display the list of movies appropriately, making your web application more dynamic and engaging.

If you continue to experience issues or have further questions, feel free to reach out or check the documentation on web components and shadow DOM for additional insights.