Salesforce JavaScript Developer Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

Custom elements are essentially user-defined HTML tags that allow developers to create their own HTML elements with specific functionality. This feature is part of the broader web components specification, a set of standards that enable the creation of reusable components with encapsulated functionality and styles.

By implementing custom elements, developers can define their own HTML tag and associate it with JavaScript behavior, making it possible to create complex elements that incorporate standard HTML functions while adding unique properties and behaviors. This extends the ability of web applications to be modular and maintainable.

For example, a developer might create a custom element called `<my-button>` that has a specific style and behavior that differs from the standard `<button>` tag. When using this custom element, any instance of `<my-button>` in the HTML would behave according to the defined specifications in the JavaScript class.

In contrast, standard HTML elements are those that are already defined by the HTML specification, and while they can be styled and manipulated using JavaScript, they do not provide the extendability that custom elements do. This distinction is crucial for understanding how custom elements enhance the capabilities of web development by allowing for unique, reusable components.