QUESTION: Что такое Web Components?

The Web Components technology is a powerful set of standardized web platform APIs that allow you to create new, custom, encapsulated, and reusable tags for use in web applications and on web pages without the need to connect third-party heavyweight libraries or frameworks like React, Vue, or Angular. This technology radically changes the approach to user interface development, making components truly independent and portable between projects.

The foundational basis of Web Components is built on several key specifications. The first of these is Custom Elements, which give developers the ability to define their own tags and fully control their lifecycle, including creation, addition to the DOM, removal, and attribute updates. The second most important component is Shadow DOM, which provides style and markup isolation. Thanks to it, the internal styles of a component will never leak outside and ruin the global design of the site, and external styles will not be able to accidentally break the layout inside the element. The third element is HTML Templates, represented by the template and slot tags, which allow defining immutable markup templates that are cloned as needed.

In practice, creating such an element looks like this: the developer creates a class extending HTMLElement, in the constructor method of which they configure the Shadow DOM and add markup to it. Then the customElements.define() method is used, linking the name of the new tag, for example my-element, with the created class. After this, the given tag can be freely used in a regular HTML document just like standard div or span elements, which ensures maximum flexibility and versatility of modern web development.