Episode 23/12: Alex Rickabaugh on Signals, Playwright 1.32
ng-news
Posted on March 29, 2023
Alex Rickabaugh, tech lead of the Angular framework, gave a "must-watch" talk, why Angular will introduce Signals. Spoiler: It is not mainly about the performance.
Playwright, an E2E testing framework, released v1.32 with a an interactive/UI mode.
Alex Rickabaugh on Signals
We had the "official Angular Meetup" where Alex Rickabaugh gave a talk on signals. As somebody who has been working on Angular for eight years and is currently the tech lead of the framework, you can expect quite a lot of deep-dive information.
He started with a little bit of history. That means jQuery, the issues it solved, and the problems it produced. Then he repeated the same thing for AngularJs until he arrived at Angular. There he discussed its current issues and how Signals would fix those.
Maybe a little surprising, he said, under the condition that you had a well-written application, he didn't expect so much in terms of performance improvements when you would switch from zone.js to signals.
According to Alex, some issues come from change detection following the component hierarchy. But, unfortunately, that is not always what we want. It shows especially in forms where the flow goes up and down and produces the famous ExpressionChange error.
Signals will fix that. Quote:
What signals do is decouple the direction of the data flow from the UI hierarchy.
In the upcoming Signal's RFC, we can also expect a detailed discussion on Signals vs. RxJs or Signals and RxJs.
You will be able to mix both Signals and zone.js. However, we have to expect to have dedicated components for Signals and zone.js in a future version.
Last but not least, Alex mentioned that pipes might become obsolete.
Playwright 1.32
We also had a new release of Playwright, an E2E testing framework. Version 1.32 was quite surprising because Playwright now comes with its own UI. Before that, you always had to use the official extension and were bound to VSCode.
Another feature of the UI is time traveling. That means you can go through the various testing steps and see what your application looked like.
That UI feature will be a game changer. Playwright was already the runner-up compared to Cypress, and that new feature will close the gap even further.
For Angular, we still have to consider that Cypress also supports Component Testing. That's not the case for Playwright.
And Cypress is next to WebdriverIO and Nightwatch, an official Angular partner in E2E testing. You can see that if you run the ng e2e command.
Posted on March 29, 2023
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