A visual guide to changing without reassigning in DECLARATIVE code

One of they key aspects of declarative code is not reassigning variables after their initial declaration... but how are we supposed to represent change in our applications if we can't reassign variables?

0:00 Introduction
0:57 Changing without reassigning
2:47 Determining the reactive graph
5:37 Error handling

#declarative #rxjs #angular

[JoshuaMorony]

Someone on reddit pointed out that the placement of the catchError would mean it only handles the first error, I've fixed this up in the source code but just be aware of that in the code shown in the video

[RasmusChristensen-nj]

It is really nice with the visualizations. It helps a lot when looking at the side-by-side with the code :) Keep it up Joshua, you are doing good work.

[SoheilMohammadi-vb]

this graph was so helpfull, I'v been trying declarative paradigm for some time, and it cleared up a lot of stuff for me that I was struggling with

[irielki]

One of your best videos to date. Excellent!

[souravsaraf]

Really loved the declarative approach as always. Can you please show a sample implmentation of this with Signals without using Rxjs ?

[mortezatourani]

Most of the time, a change in filters resets the page so I assume we can move it above the page so it also manage that

[JZubero]

Do you have an take on how to avoid reassigning when you want to subscribe to an event-style observable (e.g. ionInput of ion-searchbar) of a component that is being fetched as ViewChild (in angular)? Is there a way to work around the fact that the ViewChild/CMP reference will be undefined in the constructor scope?

[dmitriylazarenko]

Great video as usual! I’m a big fan of your channel.
I looked at the GitHub code and correct me if I’m wrong but it looks like if there be let’s say a connection error with the back end that error will not be handled because in your error handling you rely on the fact that back end returns something

[Rexyness]

Correct me if I'm wrong, but with the approach of combineLatest([page, filter]) the page will not reset (to the first page) when filter emits.

[jaybee]

In essence, create a new state from an old state, rather than mutating the old state into a new state.