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

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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

We've abstracted a single dialog's state to 

, which so far handles opening the dialog and based on the model passed through HTML attributes, displays the appropriate variant: modal or tooltip.

Modals in the application are classified as dialogs that take complete focus away from the current view. Modals typically appear in the center of the view, display a custom template, but can universally be cancelled via a button in the top right when the user clicks outside of the modal, or if the user presses the Escape key when the modal is in focus.

Tooltips are contextual dialogs that display in relation to content the user activated. Tooltips typically display beneath the content in a small dialog that can hold contextual information, usually a short phrase or instruction for the user.

The first dialog we activated in the last section was wrapped by a generic 

. In this section, we'll introduce the boilerplate for these components and begin displaying the HTML templates in the context of each Shadow DOM template. That means 

 should both be autonomous custom elements. We'll use template slots to inject the HTML templates into each component.

In this section we'll stand up the components, import them into 

 so they can be displayed in the story, integrate them with 

 and observe how they behave before proceeding to the next section.

 create a new file in the dialog directory named 

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

 from @in/common for an autonomous custom element.

import { Component, attachShadow, html, css } from "@in/common";

export class ModalComponent extends HTMLElement {
  constructor() {
    super();
    attachShadow(this, {
      mode: 'open',
    });
  }

 with a selector that specifies the custom element should be registered with the tag name 

. Provide empty template strings for the 

 properties so you can begin to fill them in.

@Component({
  selector: 'in-modal',
  style: css``,
  template: html``,
})

 is as simple as it gets. Since we're levering HTML templates for each dialog, we simply have to pass the template to a slot.

After observing the styling for a modal in Figma we need to come up with a way 

 can appear on top of the rest of the layout, while positioned at the center. This can be achieved by selecting the 

 and ensuring the custom element is a block element with 

 to be reliably positioned and sized. To center the modal, give the element 

 which roughly centers the component. Use a CSS 

 to affix the modal perfectly in the center of the view with a horizontal and vertical translation set to 

 (relative to the size of the modal). Give the modal a 

. This is a relatively high index in the 

 layering over that ensures all other elements have an opportunity to properly layer, while dialogs can always display above all other content.

:host {
  display: block;
  position: fixed;
  top: 50%;
  left: 50%;
  transform: translateX(-50%) translateY(-50%);
  width: 50vw;
  z-index: 9000;
}

We want to also fix some potential issues that could happen with elements passing through the slot. Due to giving the modal a 

 position, direct descendants of the element won't display with the appropriate size that fills out the dialog. To fix this, select all slotted elements with the pseudo selector 

---
title: Modal and Tooltip
description: You'll scaffold two custom elements that leverage DialogComponent to display modals and tooltips.
isPublicLesson: true
---

## Modal and Tooltip

We've abstracted a single dialog's state to `DialogComponent`, which so far handles opening the dialog and based on the model passed through HTML attributes, displays the appropriate variant: modal or tooltip.

Modals in the application are classified as dialogs that take complete focus away from the current view. Modals typically appear in the center of the view, display a custom template, but can universally be cancelled via a button in the top right when the user clicks outside of the modal, or if the user presses the Escape key when the modal is in focus.

Tooltips are contextual dialogs that display in relation to content the user activated. Tooltips typically display beneath the content in a small dialog that can hold contextual information, usually a short phrase or instruction for the user.

The first dialog we activated in the last section was wrapped by a generic `HTMlDivElement`. We'll change that soon. Using the `variant`, `DialogComponent` should display a `ModalComponent` or `TooltipComponent`. In this section, we'll introduce the boilerplate for these components and begin displaying the HTML templates in the context of each Shadow DOM template. That means `ModalComponent` and `TooltipComponent` should both be autonomous custom elements. We'll use template slots to inject the HTML templates into each component.

In this section we'll stand up the components, import them into `Dialog.stories.js` so they can be displayed in the story, integrate them with `DialogComponent` and observe how they behave before proceeding to the next section.

### ModalComponent

To start development on `ModalComponent` create a new file in the dialog directory named `Modal.ts`.

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

Import the relevant `function` from @in/common for an autonomous custom element.

```typescript
import { Component, attachShadow, html, css } from "@in/common";
```

Export a `class` named `ModalComponent` that extends `HTMLElement`. In the `constructor` call `attachShadow`.

```typescript
export class ModalComponent extends HTMLElement {
  constructor() {
    super();
    attachShadow(this, {
      mode: 'open',
    });
  }
```

Use the `Component` decorator to decorate the `class`, passing in the `ElementMeta` with a selector that specifies the custom element should be registered with the tag name `in-modal`. Provide empty template strings for the `style` and `template` properties so you can begin to fill them in.

```typescript
@Component({
  selector: 'in-modal',
  style: css``,
  template: html``,
})
```

The template for `ModalComponent` is as simple as it gets. Since we're levering HTML templates for each dialog, we simply have to pass the template to a slot.

```html
<slot></slot>
```

After observing the styling for a modal in Figma we need to come up with a way `ModalComponent` can appear on top of the rest of the layout, while positioned at the center. This can be achieved by selecting the `:host` and ensuring the custom element is a block element with `display: block`. This will allow every `ModalComponent` to be reliably positioned and sized. To center the modal, give the element `position: fixed` and adjust the `top` and `left` to `50%` (relative to the `document.body` which roughly centers the component. Use a CSS `transform` to affix the modal perfectly in the center of the view with a horizontal and vertical translation set to `-50%` (relative to the size of the modal). Give the modal a `z-index` set to `9000`. This is a relatively high index in the `z-index` layering over that ensures all other elements have an opportunity to properly layer, while dialogs can always display above all other content.