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

In this section, you'll prepare the UI library for distribution by optimizing the code using techniques that promote treeshaking and fast build times. You'll format the package so the directory structure is machine readable by TypeScript, which should statically analyze the package when it is a dependency of another project. Developers should be able to inspect the type definitions of each component they are importing into their project from the package. By the end of this section, you will have a library package that is compatible with build tools like Webpack, Rollup, snowpack, and esbuild.

The first thing we'll do is refactor how the components are exported from each directory in 

. So far, you only had to export anything from a file that was needed in the context of a story file, but now we have to consider how components should be exported for distribution in the UI library.

One strategy to implement here is the inclusion of a new file in each component directory: 

. The purpose of this file is to expose anything that should become part of the library, any public APIs. A tool at our disposal for exporting everything from a file that uses the 

. However, this practice causes a bottleneck for build tools that prevents them from "treeshaking" the library, removing unused parts of the library that were not directly imported into another project. Named ES2015 exports are necessary to ensure a library is treeshakable. Named exports allow build tools to statically analyze dependencies far better, enabling them to treeshake ununsed parts of the library.

In each component directory, make a new file named 

. Observe in each component file what is currently exported using the 

 keyword and export the same exports in the 

. After we walk through each component, we'll create another 

 that exports everything for the library using named ES2015 exports.

touch packages/component/src/button/index.ts

export { ButtonComponent } from "./Button";

touch packages/component/src/card/index.ts

touch packages/component/src/dialog/index.ts

Export all the necessary dialog components from the 

export { DialogStack } from "./DialogStack";
export { DialogComponent } from "./Dialog";
export { ModalComponent } from "./Modal";
export { TooltipComponent } from "./Tooltip";

touch packages/component/src/input/index.ts

Export the necessary parts for anyone to use 

export { validate, Validator } from "./validator";
export { TextInputComponent } from "./TextInput";

touch packages/component/src/table/index.ts

export { TableComponent, Column, ColumnData } from "./Table";
export { TableCardComponent } from "./TableCard";
export { TdComponent } from "./Td";
export { TrComponent } from "./Tr";

export { ButtonComponent } from "./src/button";
export { CardComponent } from "./src/card";
export {
  DialogComponent,
  DialogStack,
  ModalComponent,
  TooltipComponent,
} from "./src/dialog";
export { TextInputComponent, validate, Validator } from "./src/input";
export {
  Column,
  ColumnData,
  TableComponent,
  TableCardComponent,
  TdComponent,
  TrComponent,
} from "./src/table";

By exporting the components with named 2015 exports, you've made the entire library treeshakable. If an engineer only wanted to import 

 into their project, they can do so without bundling the rest of the library. This would not have been possible necessarily with 

. Now that you're done formatting the source code for distribution, let's consider how the package will look if we build.

---
title: Distribution
description: 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.
isPublicLesson: true
---

## Distributing Custom Element UI Libraries

In this section, you'll prepare the UI library for distribution by optimizing the code using techniques that promote treeshaking and fast build times. You'll format the package so the directory structure is machine readable by TypeScript, which should statically analyze the package when it is a dependency of another project. Developers should be able to inspect the type definitions of each component they are importing into their project from the package. By the end of this section, you will have a library package that is compatible with build tools like Webpack, Rollup, snowpack, and esbuild.

### Named Exports

The first thing we'll do is refactor how the components are exported from each directory in `packages/component/src`. So far, you only had to export anything from a file that was needed in the context of a story file, but now we have to consider how components should be exported for distribution in the UI library.

One strategy to implement here is the inclusion of a new file in each component directory: `index.ts`. The purpose of this file is to expose anything that should become part of the library, any public APIs. A tool at our disposal for exporting everything from a file that uses the `export` keyword is `export *`. However, this practice causes a bottleneck for build tools that prevents them from "treeshaking" the library, removing unused parts of the library that were not directly imported into another project. Named ES2015 exports are necessary to ensure a library is treeshakable. Named exports allow build tools to statically analyze dependencies far better, enabling them to treeshake ununsed parts of the library.

In each component directory, make a new file named `index.ts`. Observe in each component file what is currently exported using the `export` keyword and export the same exports in the `index.ts`. After we walk through each component, we'll create another `index.ts` in the root directory of the `@in/ui package` that exports everything for the library using named ES2015 exports.

Make a new file in `packages/component/src/button` named `index.ts`.

```bash
touch packages/component/src/button/index.ts
```

After observing what is exported in `Button.ts`, add another named export in `index.ts` for `ButtonComponent`.

```typescript
export { ButtonComponent } from "./Button";
```

Create another `index.ts` file in the card directory.

```bash
touch packages/component/src/card/index.ts
```

Export `CardComponent` from the new `index.ts` file.

```typescript
export { CardComponent } from "./Card";
```

Make an `index.ts` file in the dialog directory.

```bash
touch packages/component/src/dialog/index.ts
```

Export all the necessary dialog components from the `index.ts`.

```typescript
export { DialogStack } from "./DialogStack";
export { DialogComponent } from "./Dialog";
export { ModalComponent } from "./Modal";
export { TooltipComponent } from "./Tooltip";
```

Make an `index.ts` file in the input directory.

```bash
touch packages/component/src/input/index.ts
```

Export the necessary parts for anyone to use `TextInputComponent`.

```typescript
export { validate, Validator } from "./validator";
export { TextInputComponent } from "./TextInput";
```

Make an `index.ts` file in the table directory.

```bash
touch packages/component/src/table/index.ts
```

Export the necessary parts of the table.

```typescript
export { TableComponent, Column, ColumnData } from "./Table";
export { TableCardComponent } from "./TableCard";
export { TdComponent } from "./Td";
export { TrComponent } from "./Tr";
```

Export everything from `index.ts` in the `packages/component` directory.

```typescript
export { ButtonComponent } from "./src/button";
export { CardComponent } from "./src/card";
export {
  DialogComponent,
  DialogStack,
  ModalComponent,
  TooltipComponent,
} from "./src/dialog";
export { TextInputComponent, validate, Validator } from "./src/input";
export {
  Column,
  ColumnData,
  TableComponent,
  TableCardComponent,
  TdComponent,
  TrComponent,
} from "./src/table";
```

By exporting the components with named 2015 exports, you've made the entire library treeshakable. If an engineer only wanted to import `CardComponent` into their project, they can do so without bundling the rest of the library. This would not have been possible necessarily with `export *`. Now that you're done formatting the source code for distribution, let's consider how the package will look if we build.

### Build Optimizations

Building the library package for distribution means transpiling TypeScript down to a specific version of ECMAScript that is compatible with the browsers you have to support. You'll use the TypeScript compiler for this purpose. After the code is transpiled, another optimization we can provide to anyone using this package is bundling the entire library in one file that exports everything in ES2015 modules. This pattern is called a FESM (Flat ECMAScript Module). By exporting a FESM for bundlers like Webpack, you can optimize how the library is built. Since the bundler only has one file to statically analyze as opposed to many, it can reduce build times. Rollup is an excellent tool for bundling a UI library into a FESM, so we'll use it.

The necessary build files have been supplied for you in `packages/component`. Let's observe what's happening in each file. Open `packages/component/rollup.config.js`. In this file, Rollup is configured to use TypeScript and resolve dependencies from npm. When rollup builds the project, it outputs a file in `packages/component/dist/fesm2015/index.js` formatted as a FESM. Rollup also provides sourcemaps in the same directory, which can greatly enhance developer experience in some use cases like when inspecting code in Google Chrome Dev Tools.

```typescript
import typescript from "@rollup/plugin-typescript";
import nodeResolve from "@rollup/plugin-node-resolve";

export default [
  {
    input: "./index.ts",
    plugins: [nodeResolve(), typescript()],
    onwarn: (warning, next) => {
      if (warning.code === "THIS_IS_UNDEFINED") return;
      next(warning);
    },
    output: {
      file: "./dist/fesm2015/index.js",
      format: "esm",
      sourcemap: true,
    },
  },
];
```

As part of the rollup build, type definitions are outputted in `dist/fesm2015` but we want the type definitions to be outputted in the root directory of the package. To do this, we'll need to run the TypeScript compiler again and provide the following configuration in a `tsconfig.json` that tells the compiler to only emit type definitions in `dist/types`.