None of the guide pages mentions ngModules. Only `observables-in-angular` needed conversion to Standalone.
However, some of the guide pages reflect old versions of RxJS, including signatures that are no longer valid. These have been corrected.
More significantly, *the existing guide is pretty bad at explaining RxJS and its usage*. It was written (by me I think) in the very early days of Angular and Angular RxJS instruction. I've taught numerous "RxJS in Angular" classes since and learned from that experience what does and does not work with students.
There was neither the time nor the charter to completely overhaul this guide. But this commit attempts to remove what flops with students and to bring the teaching closer to what seems more effectively. I hope reviewers agree that my revisions are an improvement.
**Revised Overview**
The overview doc, `observables.md`, had a few errors (ex: `next` is NOT REQUIRED) and deprecated patterns (you now must pass the Observer object to `subscribe`).
More importantly, it was wildly overcomplicated and scary, especially when it got into multi-casting.
Moved the multi-casting section to "RxJS Library" and rewrote it (with working example) for simplicity and context.
I made other changes in an effort to make this an overview that is more comprehensive and more clear. I paid particular attention to the "Basic usage and terms" section.
Finally, I relocated the "Naming conventions for observables" section here from `rx-library`. This is the section that describes the dollar-sign convention. It made more sense for it to be here.
**Revised "RxJS Library" page and code**
*RxJS no longer supports chaining* and hasn't for a very long time. Removed note in `rx-library.md` that suggested you could use operator chaining.
The RxJS `pipe` discussion in the "Operators" section was just weird. Almost no one calls the `pipe` function. We certainly should *start* there. We should start with how people actually use operators - by adding them to the argument list of the `Observable.pipe()` method.
I kept the original `pipe` function example but subordinated it in a "callout". Most readers will (and should) ignore it.
`Subject` is a *critically important RxJS mechanism for creating custom observables*. It was completely missing from the list of observable creators on this guide page. So I added it to the "Observable creation functions" section of the guide and wrote an accompanying `MessageService` code sample (see the new `rx-library/app/` folder).
The `MessageService` is a pretty common pattern in Angular apps - far more common than creating an observable from a counter or an event, two of the creation patterns currently on this page.
This new section also afforded an opportunity to show how RxJS helps with building loosely coupled applications. We will soon be talking about Signals. Many will wonder whether and when they should still use RxJS.
At least a partial answer is that RxJS is really good at progressively combining and enhancing streams of data as they cross component boundaries. Of course you can pass signals around; but they are not as rich in transformers as RxJS. This is where RxJS shines.
**Revised "Comparing observables"**
The Promises section in `comparing-observables.md` had many errors and misleading remarks.
The comparison of error handling was especially egregious; the code example for that was nonsense.
The "Chain" sub-section was really about transforming values. It also failed to demonstrate chaining promise `.then`s.
Reworked these sub-sections and improved the code samples to match.
PR Close#51516
Switch the JS script used for running the docs examples tests from
CommonJS to ESM format. This is necessary for upgrading the `globby`
dependency to [version 12.0.0][1] in a subsequent commit.
[1]: https://github.com/sindresorhus/globby/releases/v12.0.0
PR Close#42921
Previously, the `retry` example did not work as intended. The `retry`
operator was called before the exception occured, thus not retrying the
`ajax` request.
This commit moves the `retry` operator into the correct order to ensure
that the failed request is retried.
PR Close#38905
Each docs example has an `example-config.json` configuration file. Among
other things, this file can be used to specify what commands to run in
order to test the example. (If not specified, the `run-example-e2e.js`
script will run a default `yarn e2e` command.)
Previously, the property specifying the test commands was called `e2e`.
This is because in the past only e2e tests were run for docs examples.
Since recently, some examples may specify commands for other types of
tests (such as unit tests). Therefore, calling the property that holds
the list of test commands `e2e` no longer makes sense and can be
misleading to people looking at the configuration files.
This commit renamed the property to the more generic `tests`. In the
future, the `run-example-e2e.js` script (and corresponding npm script)
should be renamed and refactored to also avoid giving the impression
that only e2e tests are run.
Discussed in:
https://github.com/angular/angular/pull/36143#discussion_r395148379
PR Close#36143
With TS 3.7, these examples were running into the error below (e.g. on https://circleci.com/gh/angular/angular/574906#tests/containers/0):
```
============== AIO example output for: /home/circleci/ng/aio/content/examples/observables/
running: yarn tsc --project ./
$ /home/circleci/ng/aio/content/examples/observables/node_modules/.bin/tsc --project ./
../../../tools/examples/shared/node_modules/protractor/built/index.d.ts(5,10): error TS2440: Import declaration conflicts with local declaration of 'PluginConfig'.
../../../tools/examples/shared/node_modules/protractor/built/index.d.ts(5,24): error TS2440: Import declaration conflicts with local declaration of 'ProtractorPlugin'.
error Command failed with exit code 2.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
completed: yarn tsc --project ./
```
This happened because of https://github.com/angular/protractor/issues/5348.
It's unclear why this typings problem does not affect `ng e2e` runs, and only affects `tsc` runs.
For now it seems sensible to alter the tests to compile only the app and not the e2e, since the intent of 2cc954d5a5 was never to verify the correctness of the e2e in the first place.
We still need a release of protractor that supports TS 3.7 though, but at least it doesn't seem to block our update proper.
PR Close#33717
Previously, some RxJS-related examples (which are not proper Angular apps) were not
tested on CI as part of the `example-e2e` npm script. This meant that the examples
could get out-of-date or contain compile errors without as noticing.
This commit ensures that the `example-e2e` script picks up these examples and checks
that they compile successfully.
Partly addresses #28017.
PR Close#34063
