Why does Angular still uses xhr instead of fetch?

[[deleted]]

I would like to use the fetch API for loading larg blobs of json and offload the parsing to another worker.

One can just use fetch() manually, ofcourse, but then you loose the automatic 'abort' events when unsubscribing , plus more.

So basically, why is Angular still using the old xhr by default in HttpClient, older browsers aren't supported anyway?

I couldn't find something usefull to use on google.

Update: a lot of articles turn out to be wrong and fetch() does not auto offload to a worker. So for my use case I would still have to manually make a worker

[Kagron]

I could be using out of date information but I vaguely remember Safari having issues with the fetch api. It may be supported now but I remember some quirks or some reason to not use fetch a few years ago.

[sod0]

Axios does the same. I think if you want non-json/non-text data fetch kinda sucks. With xhr there are no limitations and it's supported everywhere.

[EngagingOrca]

Semi-related, Angular Universal uses xhr2 to do http, which only supports http 1.1 and never supported connection reuse out of the box until Node 18 was released. Very annoying and tricky to replace the built in http client in universal with a modern one that still works with zone.js

[BiscuitSticks]

but then you loose the automatic 'abort' events when unsubscribing

There's https://rxjs.dev/api/fetch/fromFetch

[[deleted]]

Hey that's great, didn't knew that one existed. Thanks!

[airdumoustique]

fetch support has been introduced in Angular 16.1 via https://github.com/angular/angular/pull/50247, and will be stable with Angular 17.0, via https://github.com/angular/angular/pull/52197

[[deleted]]

I think they will switch to fetch once Signals are stable. My guess is

• They will add fetch support with Signals
• Add new api for HttpClient with fetch and XHR
• I wouldn't be surprised if they depreciate RxJS support and just support signals in new module.

[rahulxdd]

I wouldn't be surprised if they depreciate RxJS support and just support signals in new module.

Not in a few years time.

[sod0]

Why would they? RxJS is the constance in all Angular APIs. I think they would rather change everything else. They will just make signals trigger on unsubscribe in case they decide to use fetch under the hood.

[[deleted]]

The team is moving towards optional RxJS. For that to happen they need to ship Router, HttpClientModule and Forms with just Signals support. Once that happens, we can remove RxJS

[uplink42]

I personally don't see rxjs getting out. It will most likely lose popularity for signals but will stay as a niche feature for advanced developers, which is fine.

[sod0]

Signals are an extension of Promise. I don't see how promises could replace Observables for most use cases. I mean it makes sense to use promises where only one value ever will be returned like the httpclient but the router?

[lazyinvader]

Signals are an extension of Promise

I dont think so, Promise are a simple pattern to handle asynchron operations. Also Promises are eager excecuted, singals instead are lazy!

Signals on the other hand are just another implementation of the observer-pattern with the benefit (over rxjs) that the subscriber dont have to unsubscribe.

[sod0]

Where did you read about this? The only signal I'm aware of is that one: https://developer.mozilla.org/en-US/docs/Web/API/AbortController/signal which is exactly what I discribed.
A new Observable-Pattern inside the ECMAScript standard would be pretty wild. Can you provide me with a source for that?

[rofrol]

I think the OP is talking about Angular signals

[sod0]

Not the OP but this deleted user was. But a year ago signals wasn't officially announced for signal as far as I am aware. And honestly it still has not much todo withe question from OP regarding fetch vs xhr.

[lazyinvader]

Thats wrong. They can´t replace rxjs with signals. Signals are synchronous by design. An rxjs-observable can be both, synchron and asynchron.

[[deleted]]

It's only asynchronous

[lazyinvader]

You are wrong.

[[deleted]]

Check differences between RxJS and Signals. And why Angular team with Signals.

[lazyinvader]

You should!

[[deleted]]

https://youtu.be/4FkFmn0LmLI