As front-end developers, we often need our applications to respond to UI changes dynamically. Sometimes, these changes are based on CSS properties like visibility, color, size, or positioning. That's where Bramus CSS Observer comes into play—a powerful JavaScript tool that detects when a CSS property or element changes, allowing us to implement dynamic updates seamlessly.

In this blog, I will walk you through the key features of the Bramus CSS Observer and demonstrate a real-world example.

What is Bramus CSS Observer?

The Bramus CSS Observer is a JavaScript library designed to listen for changes in CSS properties on elements. With this observer, you can easily enable or disable certain functionalities based on real-time UI changes.

One practical example is observing the CSS borderColor of an input field to determine if it has a valid or invalid value, which could be useful for form validation.

Example Use Case

Let’s take a look at a simple example where we want to enable or disable a "Save" button based on the borderColor of an input field. If the border turns green, the input is valid, and we enable the button. Otherwise, the button stays disabled.

Here’s the code:

const observer = new CSSStyleObserver("input.style.borderColor");

observer.on("change", (style) => {
    const saveButton = document.getElementById("saveButton");

    if (style.borderColor === "green") {
        saveButton.disabled = false;
    } else {
        saveButton.disabled = true;
    }
});

In this example:

We observe changes to the borderColor property of an input field.
If the borderColor turns green, indicating valid input, we enable the "Save" button. If the borderColor is anything else, the button remains disabled.

This is particularly useful for implementing live form validation without requiring page refreshes or additional JavaScript validation logic.

How It Works

1. Set the Observer: We instantiate a new CSSStyleObserver and pass the specific CSS property (borderColor) to monitor.
2. Listen for Changes: Using the .on("change") method, we listen for any changes to the specified property.
3. Update the UI: Based on the observed changes, we enable or disable the "Save" button by toggling the disabled attribute.

Use Cases

• Form Validation: Dynamically enable or disable form submission buttons based on input validation, as demonstrated above.
• Animations: Trigger events or actions based on CSS animations.
• UI Feedback: Provide real-time feedback to users by observing style changes and reacting accordingly.

Conclusion

The Bramus CSS Observer opens up a new dimension of interactivity in your web applications. By listening for changes in CSS properties, you can create more dynamic, responsive, and user-friendly interfaces. This approach saves time and simplifies your code by utilizing existing CSS rules and eliminating the need for complex JavaScript validations or frequent DOM manipulations.

So, if you're looking to add more interactivity to your forms, UI components, or layouts, give Bramus CSS Observer a try!