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

Providing Documentation with Custom Elements Manifest and Storybook

We've got a stable library package that could be published to npm so others can reuse the components. It should be simple, right? An engineer installs the 

 package and imports the component where applicable, but then is faced with a dilemma. How does any of this work? Savvy engineers may inspect the type definitions to get a sense of how a component works, but those lack any context for the HTML attributes which are a heavily used interface for custom elements. The engineer would then have to inspect the source, which is compiled to ES2015 and wrapped in a strange decorator pattern. To solve this dilemma, we can provide documentation for the end-users of the component library.

So far, you've used Storybook as a development environment. For each use case, you coded a Story and provided a template and arguments that generated Controls for the Storybook Canvas. Storybook also has built-in tooling to display documentation for each component in the Docs tab. The first Story for each component is prioritized in the Docs tab. The user has the option to display the template in code beneath an example of the Story. When available, any HTML attributes or methods the component exposes are displayed in a table beneath the example.

By default, only the example is displayed for each Story in the Docs tab in Storybook. We need to provide additional documentation for each HTML attribute and method for Storybook to display contextual information about HTML attributes, methods, the tag name, or possibly description of the component. Storybook autogenerates the documentation with a tool called the Custom Elements Manifest. The 

 definition, parses HTML attributes, events, methods, the tag name, and description of the component and generates a JSON file which Storybook can use to configure the documentation for each Story. Custom Elements Manifest uses a CLI to run the script that generates the custom-elements.json file.

custom-elements-manifest analyze --dev --exclude "[./**/*.stories.js, dist]"

You'll eventually run the above command in the 

 file Storybook will interpret for parts of the documentation. To provide additional context around each HTML attribute or method, Storybook also interprets JSDoc comments.

 is a standardized comment pattern for documenting JavaScript inline. Any comment written in JSDoc syntax above a particular code block documents the immediately proceeding code. For instance, a JSDoc comment above a 

 definition provides contextual information about the 

, while a JSDoc comment above a method documents the method.

/**
 * Renders a dialog.
 * @tag {string} in-dialog
 * @param {string} style - css presentation
 */
@Component({

document for getting started with JSDoc is available

. In short, the multi-line JSDoc comment begins with a description of the code block, followed by contextual tags. 

. After documenting each component with JSDoc, we'll have a format Storybook can interpret while generating the documentation for each component in the UI library. As an added bonus, TypeScript should compile type definitions with the inline JSDoc comments, so engineers can read the documentation right in their IDE.

 definition with JSDoc. After providing a description, use the 

 tag to define the tag name of the component. Use 

 tags to document the necessary HTML attributes that effect the display of 

/**
 * Renders a button.
 * @tag {string} in-button
 * @attr {string} is - "in-button", Required
 * @attr {string} class - Variant, can either be "primary" "secondary", or "icon"
 */
@Component({

For Storybook to uptake these changes, you'll have to generate the 

 file which contains a JSON schema which Storybook uses to interpret each component for the documentation. We have a problem though, mostly caused by running Storybook in the context of a lerna monorepo. Storybook expects the 

 file to be in the root directory. If we ran the Custom Elements Manifest Analyzer in the 

 directory, it would generate paths to each component implementation relative to that directory and not the root directory. The analyzer expects JavaScript, not TypeScript, so we have to build the 

 package first so the tool can parse the output in the 

 with paths like in the following example:

{
  "kind": "javascript-module",
  "path": "dist/fesm2015/index.js",
  "exports": [
	{
		"kind": "js",
		"declaration": {
			"name": "ButtonComponent",
			"module": "./src/button"
		}
    }
  ]

 package, run the analyze script, further process the 

 by replacing the paths so they are relative to the root directory, then write the 

 file to the root directory. That will allow Storybook to properly interpret the manifest and display documentation for each component.

 script already cleans the dist directory, builds the library and runs the analyzer.

"analyze": "yarn clean && yarn build && custom-elements-manifest analyze --dev --exclude \"[./**/*.stories.js]\"",

lerna exec --scope @in/ui -- yarn analyze

. If you open the file you'll see paths relative to this directory. Storybook requires the same file to be placed in the root directory of the repository, so we have to update the paths programmatically everytime this script runs. To do that with node, make a new file in the 

 needed to read and write files and process paths.

import { readFile, writeFile } from "fs";
import { resolve } from "path";

, passing in the three arguments required by the 

: the path to the file, the format ("utf-8"), and the function callback where you'll process the contents of the file.

readFile(resolve("./custom-elements.json"), "utf8", (err, content) => {});

---
title: Documentation
description: Custom Elements Manifest provides a wealth of information about each component. After generating a manifest, it will provide documentation for each component in Storybook.
isPublicLesson: true
---

## Providing Documentation with Custom Elements Manifest and Storybook

We've got a stable library package that could be published to npm so others can reuse the components. It should be simple, right? An engineer installs the `@in/ui` package and imports the component where applicable, but then is faced with a dilemma. How does any of this work? Savvy engineers may inspect the type definitions to get a sense of how a component works, but those lack any context for the HTML attributes which are a heavily used interface for custom elements. The engineer would then have to inspect the source, which is compiled to ES2015 and wrapped in a strange decorator pattern. To solve this dilemma, we can provide documentation for the end-users of the component library.

So far, you've used Storybook as a development environment. For each use case, you coded a Story and provided a template and arguments that generated Controls for the Storybook Canvas. Storybook also has built-in tooling to display documentation for each component in the Docs tab. The first Story for each component is prioritized in the Docs tab. The user has the option to display the template in code beneath an example of the Story. When available, any HTML attributes or methods the component exposes are displayed in a table beneath the example.

![](https://d2uusema5elisf.cloudfront.net/courses/fullstack-web-components/module_10/lesson_10.03/public/assets/docs.png)

By default, only the example is displayed for each Story in the Docs tab in Storybook. We need to provide additional documentation for each HTML attribute and method for Storybook to display contextual information about HTML attributes, methods, the tag name, or possibly description of the component. Storybook autogenerates the documentation with a tool called the Custom Elements Manifest. The `custom-elements-manifest` package analyzes each component `class` definition, parses HTML attributes, events, methods, the tag name, and description of the component and generates a JSON file which Storybook can use to configure the documentation for each Story. Custom Elements Manifest uses a CLI to run the script that generates the custom-elements.json file.

```bash
custom-elements-manifest analyze --dev --exclude "[./**/*.stories.js, dist]"
```

You'll eventually run the above command in the `packages/component` directory that produces a `custom-elements.json` file Storybook will interpret for parts of the documentation. To provide additional context around each HTML attribute or method, Storybook also interprets JSDoc comments.

### JSDoc

[JSDoc](https://jsdoc.app) is a standardized comment pattern for documenting JavaScript inline. Any comment written in JSDoc syntax above a particular code block documents the immediately proceeding code. For instance, a JSDoc comment above a `class` definition provides contextual information about the `class`, while a JSDoc comment above a method documents the method.

```javascript
/**
 * Renders a dialog.
 * @tag {string} in-dialog
 * @param {string} style - css presentation
 */
@Component({
```

A [document for getting started with JSDoc is available](https://jsdoc.app/about-getting-started.html). In short, the multi-line JSDoc comment begins with a description of the code block, followed by contextual tags. `function` arguments can be tagged with `@param`. HTML attributes can be denoted with `@attr`. After documenting each component with JSDoc, we'll have a format Storybook can interpret while generating the documentation for each component in the UI library. As an added bonus, TypeScript should compile type definitions with the inline JSDoc comments, so engineers can read the documentation right in their IDE.

Before generating the `custom-elements.json` file, document one component in the `@in/ui` package with JSDoc.

Starting with the `ButtonComponent class` in `packages/component/src/button/Button.ts`, document the `class` definition with JSDoc. After providing a description, use the `@tag` tag to define the tag name of the component. Use `@attr` tags to document the necessary HTML attributes that effect the display of `ButtonComponent`.

```javascript
/**
 * Renders a button.
 * @tag {string} in-button
 * @attr {string} is - "in-button", Required
 * @attr {string} class - Variant, can either be "primary" "secondary", or "icon"
 */
@Component({
```

For Storybook to uptake these changes, you'll have to generate the `custom-elements.json` file which contains a JSON schema which Storybook uses to interpret each component for the documentation. We have a problem though, mostly caused by running Storybook in the context of a lerna monorepo. Storybook expects the `custom-elements.json` file to be in the root directory. If we ran the Custom Elements Manifest Analyzer in the `packages/component` directory, it would generate paths to each component implementation relative to that directory and not the root directory. The analyzer expects JavaScript, not TypeScript, so we have to build the `@in/ui` package first so the tool can parse the output in the `dist/fesm2015` directory. When that happens the `custom-elements.json` file will be written to `packages/component` with paths like in the following example:

```json
{
  "kind": "javascript-module",
  "path": "dist/fesm2015/index.js",
  "exports": [
	{
		"kind": "js",
		"declaration": {
			"name": "ButtonComponent",
			"module": "./src/button"
		}
    }
  ]
```

### Scripting the Build

You'll need to build the `@in/ui` package, run the analyze script, further process the `custom-elements.json` by replacing the paths so they are relative to the root directory, then write the `custom-elements.json` file to the root directory. That will allow Storybook to properly interpret the manifest and display documentation for each component.

The work begins in the `packages/component/package.json` file where the script is called. The `analyze` script already cleans the dist directory, builds the library and runs the analyzer.

```json
"analyze": "yarn clean && yarn build && custom-elements-manifest analyze --dev --exclude \"[./**/*.stories.js]\"",
```

Run the script using lerna.

```bash
lerna exec --scope @in/ui -- yarn analyze
```

Observe the `custom-element.json` file is outputted in the `packages/component directory`. If you open the file you'll see paths relative to this directory. Storybook requires the same file to be placed in the root directory of the repository, so we have to update the paths programmatically everytime this script runs. To do that with node, make a new file in the `packages/component` directory named `manifest.js`.