Build a Frontend Web Framework (From Scratch)

✍ Scribed by Ángel Sola Orbaiceta

• Publisher: Manning Publications
• Year: 2024
• Tongue: English
• Leaves: 386
• Edition: 1
• Category: Library

✦ Synopsis

Learn how a frontend web framework works by coding your own!

Web developers use frontend frameworks every day—but do you know how these essential parts of your stack really work? Build a Frontend Web Framework (From Scratch) reveals the inner workings of web frameworks by helping you create your very own.

In Build a Frontend Web Framework (From Scratch), you’ll learn the secrets behind frameworks like React, Vue, and Angular, including:
• Create HTML documents programmatically
• Define the view with virtual DOM
• Update the HTML efficiently with reconciliation algorithms
• Create two-way communication mechanisms between components in a hierarchy

Whatever your experience level, you’ll be able to start building your framework with this guide. All you need is some core skills in HTML, CSS, and JavaScript. And once you’ve learned how frameworks function, you’ll be able to work with them more efficiently, troubleshoot bugs more effectively, and even customize them for your specific needs!

About the technology
You use frontend frameworks every day, but do you really know what’s going on behind the API? Building your own framework is a great way to learn how they interact with the DOM, generate page views, route data between components, and communicate with the underlying operating system. With this interesting and entertaining book, you’ll build your own web framework step-by-step in JavaScript, ready to share with the world as an NPM package!

About the book
Build a Frontend Web Framework (From Scratch) guides you through a simple component-based frontend framework that borrows from React, Svelte, Angular, and other familiar tools. You’ll learn how a modern framework operates by adding features like component state and lifecycle management, a virtual DOM, and reconciliation algorithms to update the HTML efficiently. You’ll appreciate how each critical concept is broken down into easy-to-digest chunks and explained with engaging graphics.

What's inside
• Create HTML documents programmatically
• Define the view with the virtual DOM
• Implement a component lifecycle scheduler

About the reader
For web developers familiar with JavaScript and Node.

About the author
Angel Sola Orbaiceta has worked in the software industry for over a decade, creating software for the cloud, macOS, and Windows desktop applications.

✦ Table of Contents

Build a Frontend Web Framework (From Scratch)
contents
preface
acknowledgments
about this book
Who should read this book
How this book is organized: A road map
About the code
liveBook discussion forum
Other online resources
about the author
about the cover illustration
Part 1—No framework
1 Are frontend frameworks magic to you?
1.1 Why build your own frontend framework?
1.2 The framework we’ll build
1.2.1 Features
1.2.2 Implementation plan
1.3 Overview of how a frontend framework works
1.3.1 The developer’s side
1.3.2 The browser side of an SPA
1.3.3 The browser and server sides of an SSR application
Summary
2 Vanilla JavaScript— like in the old days
2.1 The assignment: A TODOs app
2.2 Writing the application
2.2.1 Project setup
2.2.2 The HTML markup
2.2.3 The JavaScript code
Summary
Part 2—A basic framework
3 Rendering and the virtual DOM
3.1 Separating concerns: DOM manipulation vs. application logic
3.2 The virtual DOM
3.3 Getting ready
3.4 Types of nodes
3.5 Element nodes
3.5.1 Conditional rendering: Removing null values
3.5.2 Mapping strings to text nodes
3.6 Text nodes
3.7 Fragment nodes
3.7.1 Implementing fragment nodes
3.7.2 Testing the virtual DOM functions
3.8 Components: The cornerstone of frontend frameworks
3.8.1 What is a component?
3.8.2 The virtual DOM as a function of the state
3.8.3 Composing views: Components as children
Summary
4 Mounting and destroying the virtual DOM
4.1 Mounting the virtual DOM
4.1.1 Mounting virtual nodes into the DOM
4.1.2 Mounting text nodes
4.1.3 Mounting fragment nodes
4.1.4 Mounting element nodes
4.1.5 Adding event listeners
4.1.6 Setting the attributes
4.1.7 A mountDOM() example
4.2 Destroying the DOM
4.2.1 Destroying a text node
4.2.2 Destroying an element
4.2.3 Destroying a fragment
Summary
5 State management and the application’s lifecycle
5.1 The state manager
5.1.1 From JavaScript events to application domain commands
5.1.2 The reducer functions
5.1.3 The dispatcher
5.1.4 Result
5.2 Assembling the state manager into the framework
5.2.1 The application instance
5.2.2 The application instance’s renderer
5.2.3 The application instance’s state manager
5.2.4 Components dispatching commands
5.2.5 Unmounting the application
5.2.6 Result
Summary
6 Publishing and using your framework’s first version
6.1 Building and publishing the framework
6.2 A short example
6.3 Refactoring the TODOs app
6.3.1 Defining the state
6.3.2 Defining the reducers
6.3.3 Defining the view
Summary
7 The reconciliation algorithm: Diffing virtual trees
7.1 The three key functions of the reconciliation algorithm
7.2 Comparing two virtual DOM trees
7.2.1 Finding the differences
7.2.2 Applying the changes
7.3 Changes in the rendering
7.4 Diffing objects
7.5 Diffing arrays
7.6 Diffing arrays as a sequence of operations
7.6.1 Defining the operations you can use
7.6.2 Finding the sequence of operations: The algorithm
7.6.3 An example by hand
7.6.4 Implementing the algorithm
Summary
8 The reconciliation algorithm: Patching the DOM
8.1 Mounting the DOM at an index
8.1.1 The insert() function
8.1.2 Text nodes
8.1.3 Element nodes
8.1.4 Fragment nodes
8.2 Patching the DOM
8.2.1 The reconciliation algorithm
8.2.2 Virtual node equality
8.2.3 Subtree change
8.2.4 Patching text nodes
8.2.5 Patching element nodes
8.2.6 Patching child nodes
8.3 Publishing the framework’s new version
8.4 The TODOs application
8.4.1 Inspecting the DOM tree changes
8.4.2 Using the paint-flashing tool (Chrome only)
Summary
Part 3—Improving the framework
9 Stateful components
9.1 Anatomy of a stateful component
9.1.1 The properties of a stateful component
9.1.2 The methods of a stateful component
9.2 Components as classes
9.3 Components with state
9.3.1 Updating the state and patching the DOM
9.3.2 Result
9.3.3 The component’s offset
9.3.4 Patching the DOM using the component’s offset
Summary
10 Component methods
10.1 Component methods
10.2 Binding event handlers to the component
10.3 Mounting the DOM with a host component
10.4 Patching the DOM with a host component
Summary
11 Subcomponents: Communication via props and events
11.1 Adding components as a new virtual DOM type
11.1.1 Updating the elements getter
11.1.2 Mounting component virtual nodes
11.1.3 Destroying component virtual nodes
11.1.4 Patching component virtual nodes
11.1.5 A rendering optimization (optional)
11.2 Events
11.2.1 Saving the event handlers inside the component
11.2.2 Extracting the props and events for a component
11.2.3 Wiring the event handlers
11.2.4 Emitting events
Summary
12 Keyed lists
12.1 The key attribute
12.1.1 Component nodes equality
12.1.2 Using the key attribute
12.1.3 Removing the key attribute from the props object
12.2 Extending the solution to element nodes
12.3 Using the key attribute
12.3.1 Mistake 1: Using the index as key
12.3.2 Mistake 2: Using the same key for different elements
12.4 The application instance
12.5 Publishing the framework
Summary
13 The component lifecycle hooks and the scheduler
13.1 The component lifecycle
13.2 Implementing the mounted and unmounted lifecycle hooks
13.2.1 Hooks asynchronicity
13.2.2 Hooks execution context
13.2.3 Dealing with asynchronicity and execution context
13.3 The scheduler
13.3.1 A simple solution that doesn’t quite work
13.3.2 Tasks, microtasks, and the event loop
13.3.3 The event loop cycle
13.3.4 The fundamentals of the scheduler
13.3.5 Implementing a scheduler
13.3.6 Scheduling the lifecycle hooks execution
13.4 Publishing version 4 of the framework
Summary
14 Testing asynchronous components
14.1 Testing components with asynchronous behavior: nextTick()
14.1.1 Testing a component with an asynchronous onMounted() hook
14.1.2 The fundamentals behind the nextTick() function
14.1.3 Implementing the nextTick() function
14.2 Publishing version 4.1 of the framework
14.3 Where to go from here
Summary
appendix—Setting up the project
A.1 Where to find the source code
A.1.1 Checking out the code for each chapter
A.1.2 A note on the code
A.1.3 Reporting problems in the code
A.1.4 Fixing a bug yourself
A.2 Solutions to the exercises
A.3 Advanced topics
A.4 Note on the technologies used
A.4.1 Package manager: NPM
A.4.2 Bundler: Rollup
A.4.3 Linter: ESLint
A.4.4 (Optional) Testing: Vitest
A.4.5 Language: JavaScript
A.5 Read the docs
A.6 Structure of the project
A.7 Finding a name for your framework
A.8 Option A: Using the CLI tool
A.9 Option B: Configuring the project from scratch
A.9.1 The examples folder
A.9.2 Creating the runtime package
A.10 Publishing your framework to NPM
A.10.1 Creating an NPM account
A.10.2 Logging in to NPM
A.10.3 Publishing your framework
A.11 Using a CDN to import the framework
index
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✦ Subjects

Web Applications; Asynchronous Programming; DOM; Testing; Frontend Development