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