Learning TypeScript (E-book) Racibórz

TypeScript has conquered the world of JavaScript. Identified in developer surveys as one of the world's fastest growing and most popular languages, TypeScript is widely used in consumer and business companies across the world and is frequently credited for helping massive web applications scale. But what exactly is TypeScript? How and why does it work, and how can we use it?This practical book takes beginner and advanced JavaScript programmers alike from knowing nothing about "types" or "type systems" to full mastery of TypeScript fundamentals.You'll learn:Benefits of TypeScript and general characteristics of its type systemWhy and how TypeScript is useful on top of "vanilla" JavaScriptHow to inform your type system by using development-only type annotationsHow TypeScript analyzes and understands code to help you augment your existing development patternsHow TypeScript helps you work with arrays, classes, functions, objects, and other important built-in JavaScript constructsHow to effectively use the plethora of TypeScript configuration options to tailor the TypeScript compiler to your teams and projectsA variety of IDE integrations such as automated refactors and intelligent code searches provided by TypeScript to help you develop quickly with fewer bugs Spis treści: Preface Who Should Read This Book Why I Wrote This Book Navigating This Book Examples and Projects Conventions Used in This Book Using Code Examples OReilly Online Learning How to Contact Us Acknowledgments I. Concepts 1. From JavaScript to TypeScript History of JavaScript Vanilla JavaScripts Pitfalls Costly Freedom Loose Documentation Weaker Developer Tooling TypeScript! Getting Started in the TypeScript Playground TypeScript in Action Freedom Through Restriction Precise Documentation Stronger Developer Tooling Compiling Syntax Getting Started Locally Running Locally Editor Features What TypeScript Is Not A Remedy for Bad Code Extensions to JavaScript (Mostly) Slower Than JavaScript Finished Evolving Summary 2. The Type System Whats in a Type? Type Systems Kinds of Errors Syntax errors Type errors Assignability Understanding Assignability Errors Type Annotations Unnecessary Type Annotations Type Shapes Modules Summary 3. Unions and Literals Union Types Declaring Union Types Union Properties Narrowing Assignment Narrowing Conditional Checks Typeof Checks Literal Types Literal Assignability Strict Null Checking The Billion-Dollar Mistake Truthiness Narrowing Variables Without Initial Values Type Aliases Type Aliases Are Not JavaScript Combining Type Aliases Summary 4. Objects Object Types Declaring Object Types Aliased Object Types Structural Typing Usage Checking Excess Property Checking Nested Object Types Optional Properties Unions of Object Types Inferred Object-Type Unions Explicit Object-Type Unions Narrowing Object Types Discriminated Unions Intersection Types Dangers of Intersection Types Long assignability errors never Summary II. Features 5. Functions Function Parameters Required Parameters Optional Parameters Default Parameters Rest Parameters Return Types Explicit Return Types Function Types Function Type Parentheses Parameter Type Inferences Function Type Aliases More Return Types Void Returns Never Returns Function Overloads Call-Signature Compatibility Summary 6. Arrays Array Types Array and Function Types Union-Type Arrays Evolving Any Arrays Multidimensional Arrays Array Members Caveat: Unsound Members Spreads and Rests Spreads Spreading Rest Parameters Tuples Tuple Assignability Tuples as rest parameters Tuple Inferences Explicit tuple types Const asserted tuples Summary 7. Interfaces Type Aliases Versus Interfaces Types of Properties Optional Properties Read-Only Properties Functions and Methods Call Signatures Index Signatures Mixing properties and index signatures Numeric index signatures Nested Interfaces Interface Extensions Overridden Properties Extending Multiple Interfaces Interface Merging Member Naming Conflicts Summary 8. Classes Class Methods Class Properties Function Properties Initialization Checking Definitely assigned properties Optional Properties Read-Only Properties Classes as Types Classes and Interfaces Implementing Multiple Interfaces Extending a Class Extension Assignability Overridden Constructors Overridden Methods Overridden Properties Abstract Classes Member Visibility Static Field Modifiers Summary 9. Type Modifiers Top Types any, Again unknown Type Predicates Type Operators keyof typeof keyof typeof Type Assertions Asserting Caught Error Types Non-Null Assertions Type Assertion Caveats Assertions versus declarations Assertion assignability Const Assertions Literals to Primitives Read-Only Objects Summary 10. Generics Generic Functions Explicit Generic Call Types Multiple Function Type Parameters Generic Interfaces Inferred Generic Interface Types Generic Classes Explicit Generic Class Types Extending Generic Classes Implementing Generic Interfaces Method Generics Static Class Generics Generic Type Aliases Generic Discriminated Unions Generic Modifiers Generic Defaults Constrained Generic Types keyof and Constrained Type Parameters Promises Creating Promises Async Functions Using Generics Right The Golden Rule of Generics Generic Naming Conventions Summary III. Usage 11. Declaration Files Declaration Files Declaring Runtime Values Global Values Global Interface Merging Global Augmentations Built-In Declarations Library Declarations Library targets DOM Declarations Module Declarations Wildcard Module Declarations Package Types declaration Dependency Package Types Exposing Package Types DefinitelyTyped Type Availability Summary 12. Using IDE Features Navigating Code Finding Definitions Finding References Finding Implementations Writing Code Completing Names Automatic Import Updates Code Actions Renaming Removing unused code Other quick fixes Refactoring Working Effectively with Errors Language Service Errors Problems tab Running a terminal compiler Understanding types Summary 13. Configuration Options tsc Options Pretty Mode Watch Mode TSConfig Files tsc --init CLI Versus Configuration File Inclusions include exclude Alternative Extensions JSX Syntax jsx Generic arrow functions in .tsx files resolveJsonModule Emit outDir target Emitting Declarations emitDeclarationOnly Source Maps sourceMap declarationMap noEmit Type Checking lib skipLibCheck Strict Mode noImplicitAny strictBindCallApply strictFunctionTypes strictNullChecks strictPropertyInitialization useUnknownInCatchVariables Modules module moduleResolution Interoperability with CommonJS esModuleInterop allowSyntheticDefaultImports isolatedModules JavaScript allowJs checkJs @ts-check JSDoc Support Configuration Extensions extends Extending modules Configuration Bases Project References composite references Build Mode Coordinator configurations Build-mode options Summary IV. Extra Credit 14. Syntax Extensions Class Parameter Properties Experimental Decorators Enums Automatic Numeric Values String-Valued Enums Const Enums Namespaces Namespace Exports Nested Namespaces Namespaces in Type Definitions Prefer Modules Over Namespaces Type-Only Imports and Exports Summary 15. Type Operations Mapped Types Mapped Types from Types Mapped types and signatures Changing Modifiers Generic Mapped Types Conditional Types Generic Conditional Types Type Distributivity Inferred Types Mapped Conditional Types never never and Intersections and Unions never and Conditional Types never and Mapped Types Template Literal Types Intrinsic String Manipulation Types Template Literal Keys Remapping Mapped Type Keys Type Operations and Complexity Summary Glossary Index