Rxjs in Action

Description

A growing flood of data is aimed at JavaScript applications, and they need be ready for it. As more and more data is received, applications must scale to stay operational. There's also the problem of latency when data has to be fetched from remote locations. RxJS, or Reactive Extensions for JavaScript, is a library for transforming, composing, and consuming streams of data. RxJS combines reactive and functional programming to give an extensible, asynchronous event handling system for JavaScript. RxJS in Action gives readers the development skills they need to create reactive applications with RxJS. This book is full of theory and practical examples that build on each other and help readers begin thinking in a reactive manner. The book begins by teaching the fundamentals of functional programming, and dives in to the basics of RxJS and what it means to be reactive. Next, it teaches how to build real-world applications with RxJS. The last part of the book tackles the advanced topics to take the reader's reactive programming skills to the next level, as they will learn how to deal with error handling, unit testing, and the role of RxJS when combined with frameworks such as Angular.js or Cycle.js. Examples in the book use RxJS 5, the latest version of RxJS built with an eye on performance and simplicity. Purchase of the print book includes a free eBook in PDF, Kindle, and ePub formats from Manning Publications. brief contents contents foreword preface acknowledgments about this book Road map Who should read this book How to use this book Examples and source code Author Online about the authors about the cover Part 1 Understanding streams 1 Thinking reactively 1.1 Synchronous vs. asynchronous computing 1.1.1 Issues with blocking code 1.1.2 Non-blocking code with callback functions 1.1.3 Understanding time and space 1.1.4 Are callbacks out of the picture? 1.1.5 Event emitters 1.2 Better callbacks with Promises 1.3 The need for a different paradigm 1.4 The Reactive Extensions for JavaScript 1.4.1 Thinking in streams: data flows and propagation 1.4.2 Introducing the RxJS project 1.4.3 Everything is a stream 1.4.4 Abstracting the notion of time from your programs 1.4.5 Components of an Rx stream 1.5 Reactive and other programming paradigms 1.6 Summary 2 Reacting with RxJS 2.1 Functional programming as the pillar of reactive programming 2.1.1 Functional programming 2.1.2 The iterator pattern 2.2 Stream’s data-driven approach 2.3 Wrapping data sources with Rx.Observable 2.3.1 Identifying different sources of data 2.3.2 Creating RxJS observables 2.3.3 When and where to use RxJS 2.3.4 To push or not to push 2.4 Consuming data with observers 2.4.1 The Observer API 2.4.2 Creating bare observables 2.4.3 Observable modules 2.5 Summary 3 Core operators 3.1 Evaluating and cancelling streams 3.1.1 Downside of eager allocation 3.1.2 Lazy allocation and subscribing to observables 3.1.3 Disposing of subscriptions: explicit cancellation 3.1.4 Cancellation mismatch between RxJS and other APIs 3.2 Popular RxJS observable operators 3.2.1 Introducing the core operators 3.3 Sequencing operator pipelines with aggregates 3.3.1 Self-contained pipelines and referential transparency 3.3.2 Performance advantages of sequencing with RxJS 3.4 Summary 4 It’s about time you used RxJS 4.1 Why worry about time? 4.2 Understanding asynchronous timing with JavaScript 4.2.1 Implicit timing 4.2.2 Explicit timing 4.2.3 The JavaScript timing interfaces 4.3 Back to the future with RxJS 4.3.1 Propagation 4.3.2 Sequential time 4.4 Handling user input 4.4.1 Debouncing 4.4.2 Throttling 4.5 Buffering in RxJS 4.6 Summary Part 2 Observables in practice 5 Applied reactive streams 5.1 One for all, and all for one! 5.1.1 Interleave events by merging streams 5.1.2 Preserve order of events by concatenating streams 5.1.3 Switch to the latest observable data 5.2 Unwinding nested observables: the case of mergeMap 5.3 Mastering asynchronous streams 5.4 Drag and drop with concatMap 5.5 Summary 6 Coordinating business processes 6.1 Hooking into the observable lifecycle 6.1.1 Web hooks and the observer pattern 6.1.2 Hooked on observables 6.2 Joining parallel streams with combineLatest and forkJoin 6.2.1 Limitations of using Promises 6.2.2 Combining parallel streams 6.2.3 More coordination with forkJoin 6.3 Building a reactive database 6.3.1 Populating a database reactively 6.3.2 Writing bulk data 6.3.3 Joining related database operations 6.3.4 Reactive databases 6.4 Summary 7 Error handling with RxJS 7.1 Common error-handling techniques 7.1.1 Error handling with try/catch 7.1.2 Delegating errors to callbacks 7.1.3 Errors and Promises 7.2 Incompatibilities between imperative error-handling techniques and functional and reactive code bases 7.3 Understanding the functional error-handling approach 7.4 The RxJS way of dealing with failure 7.4.1 Errors propagated downstream to observers 7.4.2 Catching and reacting to errors 7.4.3 Retrying failed streams for a fixed number of times 7.4.4 Reacting to failed retries 7.5 Summary Part 3 Mastering RxJS 8 Heating up observables 8.1 Introducing hot and cold observables 8.1.1 Cold observables 8.1.2 Hot observables 8.2 A new type of data source: WebSockets 8.2.1 A brief look at WebSocket 8.2.2 A simple WebSocket server in Node.js 8.2.3 WebSocket client 8.3 The impact of side effects on a resubscribe or a replay 8.3.1 Replay vs. resubscribe 8.3.2 Replaying the logic of a stream 8.3.3 Resubscribing to a stream 8.4 Changing the temperature of an observable 8.4.1 Producers as thermometers 8.4.2 Making a hot observable cold 8.4.3 Making a cold observable hot 8.4.4 Creating hot-by-operator streams 8.5 Connecting one observable to many observers 8.5.1 Publish 8.5.2 Publish with replay 8.5.3 Publish last 8.6 Summary 9 Toward testable, reactive programs 9.1 Testing is inherently built into functional programs 9.2 Testing asynchronous code and promises 9.2.1 Testing AJAX requests 9.2.2 Working with Promises 9.3 Testing reactive streams 9.4 Making streams testable 9.5 Scheduling values in RxJS 9.6 Augmenting virtual reality 9.6.1 Playing with marbles 9.6.2 Fake it ’til you make it 9.6.3 Refactoring your search stream for testability 9.7 Summary 10 RxJS in the wild 10.1 Building a basic banking application 10.2 Introduction to React and Redux 10.2.1 Rendering UI components with React 10.2.2 State management with Redux 10.3 Redux-ing application state 10.3.1 Actions and reducers 10.3.2 Redux store 10.4 Building a hot RxJS and Redux store adapter 10.5 Asynchronous middleware with RxJS Subject 10.5.1 RxJS subjects 10.5.2 Building epic, reactive middleware 10.6 Bringing it all home 10.7 Parting words 10.8 Summary Appendix A Installation of libraries used in this book Installing the example projects Installing RxJS Installing Ramda.js Installing PouchDB Installing Moment.js Installing Google client APIs Using the Bitly Web API Installing Mocha Installing Chai.js Installing React.js Installing React-Bootstrap Installing Redux.js Appendix B Choosing an operator index Symbols A B C D E F G H I J K L M N O P R S T U V W X Z