Angular Development with TypeScript, Second Edition

Appendix D. RxJS essentials

Synchronous programming is relatively straightforward in that each line of your code is executed after the previous one. If you invoke a function in line 25 that returns a value, you can use the returned value as an argument for the function invoked in line 26.

Asynchronous programming dramatically increases code complexity. In line 37, you can invoke an asynchronous function that will return the value sometime later. Can you invoke a function in line 38 that uses the value returned by the previous function? The short answer is, “It depends.”

This appendix is an introduction to the RxJS 6 library, which can be used with any JavaScript-based app. It shines when it comes to writing and composing asynchronous code. ...