Ultimate Typescript Handbook: Build, scale and maintain Modern Web Applications with Typescript

Cover Page....1

Title Page....2

Copyright Page....3

Dedication Page....4

About the Author....5

Technical Reviewers....6

Acknowledgements....7

Preface....8

Errata....11

Table of Contents....14

1. Introduction to TypeScript and its Benefits....24

Introduction....24

Structure....24

Introduction to TypeScript....24

A short history of TypeScript....25

Main components of TypeScript....25

TypeScript’s type system....26

Advantages of using TypeScript....27

Catching bugs....27

Readability....28

Refactoring....29

Future language features....29

Disadvantages of TypeScript....30

The ways in which TypeScript prevents bugs....31

Steps to begin using TypeScript....32

Type-driven development....35

Conclusion....37

References....37

2. Setting up a Development Environment....39

Introduction....39

Structure....39

Installing dependencies....40

Version numbers....40

Installing Node.js On Windows....40

Installing Node.js on Mac....41

Installing a code editor....42

Installing TypeScript globally....42

Creating a new TypeScript project....43

The tsconfig.json file....44

Installing TypeScript locally to a project....45

Configuring TypeScript with tsconfig.json....46

Default enabled configuration options....47

target....47

module....48

esModuleInterop....49

forceConsistentCasingInFileNames....49

strict....49

skipLibCheck....51

Commonly used configuration options....51

files....51

include....52

exclude....52

baseUrl....52

rootDir....52

paths....53

outDir....53

resolveJsonModule....54

Top-level configuration options....54

Updating the project configuration....54

Enabling TypeScript checking in JavaScript....55

Default behavior....56

Enabling type checking....57

Adding JSDoc annotations....58

Example project structure and use....61

Conclusion....61

References....62

3. Basic Type Annotations....63

Introduction....63

Structure....63

Primitive types....64

BigInt....64

Boolean....66

Number....66

Null....67

String....68

Symbol....68

Undefined....69

The any type....70

The unknown type....72

The never type....73

The as operator....74

Down-casting....74

Compound casting....75

Older type-casting syntax....77

Union types....78

Literal types....79

Literal union types....80

Type aliases....81

Type assertion....83

Non-null assertion operator....85

Conclusion....85

References....87

4. Using the TypeScript Compiler....88

Introduction....88

Structure....88

Compiling our TypeScript files....89

Inspecting compiled files....94

CLI flags....95

--version....96

--listFilesOnly....98

--showConfig....100

--help....102

Using watch mode....103

watchFile....105

watchDirectory....106

fallbackPolling....106

synchronousWatchDirectory....107

excludeDirectories....107

excludeFiles....108

assumeChangesOnlyAffectDirectDependencies....108

Environment variables....108

Building projects....109

Build-specific flags....113

Integrating with other build tools....115

Integrating with webpack....115

TypeScript webpack configuration....116

Using third-party libraries....119

Generating .d.ts files....121

Generating d.ts files from .js files....123

Conclusion....126

References....127

5. Enums, Interfaces, and Namespaces....128

Introduction....128

Structure....128

Interfaces....129

Interface merging....134

Extending interfaces....135

Namespaces....138

Namespace merging....140

Enums....141

Numeric enums....142

Reverse mapping....146

Exhaustiveness and the never type....146

String enums....149

Heterogeneous enums....151

Computed and constant enums....153

Literal enums....154

Inlining enums....156

Using the keyof operator....158

Conclusion....159

References....159

6. Objects, Arrays, and Tuples in TypeScript....160

Introduction....160

Structure....160

Arrays....161

Array type inference....162

Read-only arrays....164

Tuples....165

Optional elements in tuples....168

Rest elements in tuples....168

Read-only tuples....169

Object types....169

Property modifiers....174

Index signatures....175

Intersections....176

Generic object types....178

Readonly utility type....180

Conclusion....181

References....182

7. Functions in TypeScript....183

Introduction....183

Structure....183

Parameter Type and Return Type Annotations....184

Type Inference for Functions....186

Arrow Functions....187

Type Inference for Arrow Functions....189

Optional Parameters....189

Rest Parameters....190

Rest Arguments....191

Destructured Parameters....192

Void return type....195

Function Type Expressions....197

Call signatures....198

Function Type Interfaces....200

This Parameter....201

Function overloads....203

Overloading Arrow Functions....205

Generator functions....207

Generic functions....213

Generic Function Constraints....214

Conclusion....216

References....216

8. Classes in TypeScript....218

Introduction....218

Structure....218

Class Declarations....219

Class Expressions....220

Constructors....220

Constructor Overloading....223

Parameter Properties....224

Access Modifiers....225

Private Members in JavaScript....227

Getters and Setters....228

This Parameter....230

Index Signatures....232

Implementing an Interface....233

Static Class Members....234

Static Blocks....235

Inheritance....237

Abstract Classes....240

Abstract Properties....241

Abstract Methods....242

Generic Classes....243

Decorators....245

TypeScript Design Patterns....246

Conclusion....249

References....249

9. Control Flow Analysis....250

Introduction....250

Structure....250

Narrowing....251

Widening....252

Type Guards....253

Truthiness Type Guards....254

Narrowing with Typeof....255

Handling null Values....256

Narrowing with Instanceof....257

Narrowing with the in Operator....259

Narrowing with Type Predicates....260

Discriminated Unions....263

Assertion Functions....264

Using as const....268

Conclusion....272

References....272

10. Manipulating Types....273

Introduction....273

Structure....273

Generics....273

Generic Interfaces....274

Generic Types....274

Generic Classes....275

Generic Functions....275

Conditional Types....277

Indexed Access Types....278

Mapped Types....279

Adding and Removing Property Modifiers....280

Remapping Property Keys....282

Template Literal Types....283

Capitalize....285

Uncapitalize....286

Uppercase....286

Utility Types....287

Awaited....287

ConstructorParameters....288

Exclude....290

Extract....291

InstanceType....292

NonNullable....294

Omit....296

OmitThisParameter....297

Partial....299

Parameters....301

Pick....302

Readonly....303

Record....305

Required....306

ReturnType....308

ThisParameterType....309

ThisType....310

Conclusion....311

References....312

11. TypeScript Modules....313

Introduction....313

Structure....313

Modules in TypeScript....313

Importing and exporting modules....314

Type-only imports and exports....316

Compiled modules....316

Module-related configuration options....318

Module....319

Module resolution....321

Base URL....322

Paths....322

Rootdirs....323

Type roots....324

Module suffixes....324

Resolve JSON module....325

Module resolution....326

Compiler directives....328

Reference path....329

Reference types....330

Reference lib....331

No default lib....331

AMD module....331

AMD dependency....331

Barrel files....332

Nested barrels....334

Augmenting modules....335

Conclusion....336

References....336

12. Creating Declaration Files....338

Introduction....338

Structure....338

Creating declaration files....339

Declaring global libraries....339

Enhancing Intellisense with JSDoc....342

Declaring global functions and variables....344

Augmenting built-ins....345

Declaring modular libraries....346

Declaring default exports....348

Declaring classes....350

Declaring CommonJS modules....351

Declaring UMD modules....352

Publishing declarations....355

Publishing with the library....355

Publishing to Definitely Typed....356

Testing types....360

Conclusion....362

References....362

13. Building a Conference App with Angular and TypeScript....364

Introduction....364

Structure....364

Getting started....365

Running build tasks....369

Unit tests....369

Linting....371

Serving the application....374

Creating the application shell....376

Creating a data model....379

Adding views....382

Home view....382

Adding routing....388

Building the add-conference view....390

Adding the conferences view....400

Changing the default locale....408

Adding a page not found component....411

Handling data....414

Unit testing....425

Continuing with the example application....428

Conclusion....429

References....429

Index....431

This book provides a comprehensive guide to TypeScript, a programming language that extends JavaScript with powerful features like static typing, classes, and interfaces. The book is divided into thirteen chapters that cover everything from setting up a development environment to building an Angular app with TypeScript.We start with an introduction to TypeScript and its benefits and go on to explain how TypeScript can help developers write more maintainable, scalable code and catch errors before they make it to production. The book then dives into more technical topics like basic type annotations, using the TypeScript compiler, advanced features like enums and interfaces, and manipulating types.The book then discusses chapters on classes and control flow analysis that are particularly helpful for developers looking to build more complex applications. The book teaches by example, with numerous code examples that illustrate the main concepts and approaches towards writing TypeScript programs and codes, and finishes with a comprehensive practical example that shows step-by-step development of a modern web application using TypeScript and Angular.

What you will learn

• Learn how to create a new TypeScript project with default settings and configurations.
• Discover how to incorporate basic type-annotations into your code for improved clarity and accuracy.
• Explore the use of type-aliases, interfaces, and enums to write more organized and expressive TypeScript code.
• Gain knowledge on building modular and error-free applications in TypeScript.
• Discover how to leverage type-guards, classes, and other TypeScript utilities to write more robust code.
• Learn how to work with advanced features like generics and take your TypeScript skills to the next level.

Who is this book for?

This book is targeted towards front-end developers who are familiar with JavaScript and are interested in expanding their skillset with TypeScript. Whether you are a beginner with little to no experience or an intermediate developer looking for a reference guide, this book is designed to help you supercharge your development and enhance your tooling. With its clear and concise explanations, it's perfect for those who are new to TypeScript and looking to gain a deeper understanding of its capabilities.