Acknowledgements

The beginning of your journey with Web Components.

Foreword

A brief introduction to the set of specifications called Web Components. We'll introduce you to concepts such as Shadow DOM, HTML templates, Custom Elements v1 and uncover typical use cases for developing Web Components.

Introduction to Web Components

We'll introduce you to the mockups in Figma, the development environment used throughout the book, and other conventions used in this book.

Conventions Used In The Book

A guide for installing various technologies needed prior to coding the exercises in this book.

Setting Up The Development Environment

We'll look at what you'll learn throughout Fullstack Web Components.

Module 1 Summary

Introduction

In Part 1, you'll code a form using several Web Components specifications.

Specification

Part One

By developing the CardComponent, you'll get hands on experience with autonomous custom elements.

Autonomous custom elements

Before you can develop the CardComponent, you'll need to scaffold the component in Storybook.

Template Slots

Shadow DOM provides encapsulation for styling and template. You'll style CardComponent with CSS in the context of the autonomous custom element's Shadow DOM.

Styling CardComponent

Write integration and snapshot tests for CardComponent using Cypress and Storybook Storyshots.

Testing the card

You built an autonomous custom element with Shadow DOM, HTML templates, and ES Modules. Let's reflect on that.

Chapter One Summary

Getting to Know Web Components

Form-associated custom elements allow custom elements to participate in HTML forms. From validation to submission, you'll code a text input end-to-end.

Form-associated custom elements

Scaffold a form-associated custom element named TextInputComponent in Storybook.

TextInputComponent

You'll learn what distinguises a form-associated custom element from an autonomous custom element, the formAssociated property and ElementInternals interface.

Form Associated and ElementInternals

Form-associated custom elements don't come with a pattern that validates an entire form, so you'll implement a pattern that allows form validation.

Handling Validation

Using observedAttributes and attributeChangedCallback to listen and react to changes in custom element attributes.

Listening for attribute changes

You'll style the various interaction states of the TextInputComponent form-associated custom element.

User feedback

We've created a problem by encapsulating the HTMLInputElement by Shadow DOM. The HTMLInputElement API cann't be accessed by the outside world. In this section, you'll fix that by implementing getters and setters that emulate the HTMLInputElement on TextInputComponent.

Emulating HTMLInputElement

You'll update the Story and provide the missing APIs to TextInputComponent that allow the component to fully interact with a HTML form.

Making a form

Reviewing the work completed on the form-associated custom element TextInputComponent.

Chapter Two Summary

You'll code ButtonComponent, a customized built-in element that inherits accessibility characteristics from HTMLButtonElement.

Customized built-in elements

Scaffold the customized built-in element ButtonComponent with Storybook.

Scaffolding ButtonComponent

Customized built-ins can't benefit from the encapsulation provided by Shadow DOM, so you'll have to find another way to style ButtonComponent.

Styling ButtonComponent

Revist the HTML form by making the user experience more accessible.

Making the form accessible

How customized built-in elements can make custom elements more accessible.

Chapter Three Summary

You'll learn best practices for developing a UI Library with Web Components by coding a micro-library, developing two custom elements with the micro-library, and figuring out how to package the UI library for distribution.

UI Library

Part Two

You'll abstract common patterns intro reusable code in a micro-library powered by TypeScript Decorators.

Micro-library

How to code an interface for Web Components with TypeScript decorators that enables declaration of the selector, styles, and template.

Class Decorator

You'll code a method decorator named Listen that binds event listeners to class methods.

Method Decorator

In this chapter you learned how to code a micro-library with TypeScript decorators that streamlines Web Component development.

Chapter Four Summary

You'll investigate multiple methods for components to communicate by coding an editable table.

Component Communication

How to use mock data in Storybook to code Web Components.

Mocking Table Data in Storybook

You'll learn about three methods for custom elements to communicate, attribute drilling, CustomEvent, and BroadcastChannel.

Coding Compound Components

You'll learn about how to create a separation of concerns between the many custom elements that comprise the editable table.

Making the Table Editable

You learned about how to create a separation of concerns between various custom elements in the same user experience flow.

Summary

Compound Custom Elements

You'll learn how to code a common UX pattern (dialogs) using HTML templates and custom elements.

HTML Templates

You'll mock the DialogComponent in Storybook.

Mocking the Dialog in Storybook

You'll make a configurable dialog with custom elements.

DialogComponent

You'll scaffold two custom elements that leverage DialogComponent to display modals and tooltips.

Modal and Tooltip

You'll fix an issue faced in the last section by learning how to query for elements across Shadow boundaries.

Querying DOM Across Shadow Boundaries

You'll control the ordering and event cycle of dialogs with a custom class named DialogStack.

DialogStack

Summarizing the work completed in DialogComponent, ModalComponent, TooltipComponent, and DialogStack.

Chapter Six Summary

Powering Dialogs with HTML Templates

You'll learn best practices for organizing and distributing Web Component UI libraries.

UI Libraries

You'll learn brest practices for distributing Web Components by formatting the code with named exports, configuring the build with Rollup, providing a standard package format, and writing a custom Node.js script that enables you to publish packages.

Distribution

Custom Elements Manifest provides a wealth of information about each component. After generating a manifest, it will provide documentation for each component in Storybook.

Documentation

You'll learn how to setup continuous integration for the UI library with Github Actions.

Continuous Integration

Let's reflect on the best practices you learned for distributing UI libraries filled with Web Components.

Chapter Seven Summary

Distributing Custom Element Libraries

You'll integrate the UI library with a single-page application and code the end-to-end user experience with custom elements.

Application

Part Three

You'll provide a separation of concerns with custom elements in a single page application.

Application Development with Custom Elements

You'll scaffold the landing page with an autonomous custom element named MainView.

Landing Page

You'll code a global header with autonomous custom elements named AppHeader.

Header

You'll code another autonomous custom element that handles cookie authorization named CookieFooter.

CookieFooter

You'll lazyload an image with customized built-ins.

Background

You developed the landing page of the application, learning how to architect a separation of concerns between the UI components.

Chapter Eight Summary

To handle multiple views in the single page application, you'll need to implement a router that can navigate between each view.

Routing Custom Elements in a SPA

You'll code the Router class that handles the creation and removal of views in the application.

Routing

You'll code the necessary components and services required in the login view.

Login View

Integrate TableCardComponent into a third view of the single page application, the dashboard.

Dashboard View

You coded a single page web application with custom elements and a custom router.

Chapter Nine Summary

You'll server-side render the views of the application with Declarative Shadow DOM and @lit-labs/ssr

Server-Side Rendering Custom Elements

You'll declare a server-side renderable Declarative Shadow DOM HTML template for each component.

Declarative Shadow DOM Templates

To get custom elements to work in Node.js, you'll need to polyfill DOM APIs. Luckily, @lit-labs/ssr provides a tool that enables just that.

Shim

You'll develop Express middleware that server-side renders Declarative Shadow DOM HTML Templates with @lit-labs/ssr.

Express Middleware

You rendered custom elements server-side using Declarative Shadow DOM and @lit-labs/ssr.

Chapter Ten Summary

Server-side Rendering with Declarative Shadow DOM

The conclusion of the book Fullstack Custom Elements.

Conclusion

Fullstack Web Components

Enter your name and email address below, then click the **"Send my free chapter"** button to get started

There are several books about Web Components, but none go into how to integrate Web Components in a typical enterprise web development workflow. This book is designed to help you learn Web Components and integrate it into your work.

In this book, we cover the basics of Web Components, how to code complex user interfaces with custom elements in Storybook, how to test and maintain UI libraries built with custom elements, and how to build web applications entirely with Web Components and browser specifications. It comes with complete code examples. We walk through the entire process step-by-step.

It's taught by Stephen Belovarich, a software engineer and web developer. Stephen has provided what he's learned about UI libraries and web applications while working at Ubiquiti Networks, Norton, Nike, NBC Universal, and Workday, that can benefit other developers, students, and anyone making a website.

The Complete Guide to Building UI Libraries with Web Components

In this book, we will learn Web Components through the lens of a JavaScript developer.

The basics of working with and manipulating Web Components

The best practices for maintaining a UI library made of custom elements

How to create a micro-library for Web Components with TypeScript Decorators

What problems Web Components can solve in everyday development

How to build web applications entirely from Web Components and JavaScript

Cooperation between design and engineering in large enterprise organizations is crucial to ensure scalability and maintainability for a codebase. That cooperation often happens at the level of a UI library, a collection of user interfaces that handle repeatable views in an application. Figma connects everyone involved in the design process, giving designers a venue to publish UI designs and other stakeholders the ability to comment and interact with the design.

Design teams often follow the principals of atomic design, a philosophy popularized by designer and developer 

 prescribes an architecture that begins at the smallest units: atoms, and scales into molecules and organisms. As this happens, the more complex the user interface becomes. Organisms are comprised of molecules, molecules are comprised of atoms. You've experienced this design pattern while developing the many user interfaces in this book. CSS variables that represent design tokens serve as atoms. 

 are organisms. Understanding the atomic design pattern is paramount when designing and developing a UI library.

When realized in the context of a UI library, atomic design promotes a separation of concerns between UI components when components are built with a strict separation of concerns. If the user interfaces are built once and distributed across an organization in a UI library, it promotes consistency and uniformity across a product. UI libraries can reduce maintenance overhead. Unnecessary churn could happen if teams were to code the same user interfaces in many different ways. UI libraries built with JavaScript frameworks and libraries have the cost of dependency maintenance, an issue that is substantially reduced when UI libraries are built entirely with browser specifications.

UI libraries can be developed in such a way that allows engineers to move fast and build features. Exporting discrete units of functionality promotes reuse. Distributing components that handle complex user interaction patterns is much more difficult. Suppose a team wanted to use 

 but needed the additional feature of selecting multiple rows. There isn't a mechanism in the library yet for a user interface that allows toggling something, like a checkbox. If a 

 were already developed, adding one to each row of 

 would be tricky to avoid breaking changes, the feature would have to be opted in, probably by setting a HTML attribute. Making components like 

 composable is difficult in any library, but possible. You've already abstracted each row and cell to separate components. The 

 could be extended to enhance them with other functionality. This example is just one of many problems that can arise because of how components are architected; however, by exporting the discrete units of functionality that comprise complex components, you can retain design characteristics and user experience behaviors while giving teams the opportunity to construct custom user experiences.

How UI libraries are integrated and distributed in an enterprise organization's development pipeline are as critical to their success as how they are architected. Continuous integration ensures that code which can't be properly built or tested isn't being introduced into the main branch of a repository. Although integration depends largely on the tooling that is available, in this chapter, you'll learn how to set up a continuous integration pipeline with Github Actions. By implementing a package format that teams can easily install and import, you'll implement best practices for distributing a UI library of Web Components.

In this chapter, you'll learn how to validate a pull request in Github by running integration and snapshot tests via Github Actions. Cypress and Storyshots both require Storybook to be properly built, so you'll learn how to run Storybook with Github Actions. When an engineer creates a pull request in Github, it's also a good idea to check the build is successful, otherwise the project cannot be properly built before it's deployed. Typically, deployment of any npm packages happens when a PR meets some criteria after being merged to the main branch. You'll set up everything in Github Actions leading up to that point, while also deploying Storybook to Github Pages to observe the current state of the components after merging to the main branch.

---
title: UI Libraries
description: You'll learn best practices for organizing and distributing Web Component UI libraries.
role: "INTRODUCTION"
isPublicLesson: true
---

# Chapter Seven

## UI Libraries

### Design and Engineering

Cooperation between design and engineering in large enterprise organizations is crucial to ensure scalability and maintainability for a codebase. That cooperation often happens at the level of a UI library, a collection of user interfaces that handle repeatable views in an application. Figma connects everyone involved in the design process, giving designers a venue to publish UI designs and other stakeholders the ability to comment and interact with the design.

Design teams often follow the principals of atomic design, a philosophy popularized by designer and developer [Brad Frost](https://bradfrost.com). [Atomic design](https://shop.bradfrost.com) prescribes an architecture that begins at the smallest units: atoms, and scales into molecules and organisms. As this happens, the more complex the user interface becomes. Organisms are comprised of molecules, molecules are comprised of atoms. You've experienced this design pattern while developing the many user interfaces in this book. CSS variables that represent design tokens serve as atoms. `TextInputComponent`, `CardComponent` could be considered molecules, while `TableComponent` or `DialogComponent` are organisms. Understanding the atomic design pattern is paramount when designing and developing a UI library.

When realized in the context of a UI library, atomic design promotes a separation of concerns between UI components when components are built with a strict separation of concerns. If the user interfaces are built once and distributed across an organization in a UI library, it promotes consistency and uniformity across a product. UI libraries can reduce maintenance overhead. Unnecessary churn could happen if teams were to code the same user interfaces in many different ways. UI libraries built with JavaScript frameworks and libraries have the cost of dependency maintenance, an issue that is substantially reduced when UI libraries are built entirely with browser specifications.

UI libraries can be developed in such a way that allows engineers to move fast and build features. Exporting discrete units of functionality promotes reuse. Distributing components that handle complex user interaction patterns is much more difficult. Suppose a team wanted to use `TableComponent` but needed the additional feature of selecting multiple rows. There isn't a mechanism in the library yet for a user interface that allows toggling something, like a checkbox. If a `CheckboxComponent` were already developed, adding one to each row of `TableComponent` would be tricky to avoid breaking changes, the feature would have to be opted in, probably by setting a HTML attribute. Making components like `TableComponent` composable is difficult in any library, but possible. You've already abstracted each row and cell to separate components. The `TrComponent` and `TdComponent` `class` could be extended to enhance them with other functionality. This example is just one of many problems that can arise because of how components are architected; however, by exporting the discrete units of functionality that comprise complex components, you can retain design characteristics and user experience behaviors while giving teams the opportunity to construct custom user experiences.

### Continuous Integration

How UI libraries are integrated and distributed in an enterprise organization's development pipeline are as critical to their success as how they are architected. Continuous integration ensures that code which can't be properly built or tested isn't being introduced into the main branch of a repository. Although integration depends largely on the tooling that is available, in this chapter, you'll learn how to set up a continuous integration pipeline with Github Actions. By implementing a package format that teams can easily install and import, you'll implement best practices for distributing a UI library of Web Components.