Upgrade to Angular 16

[tdonohue]

Angular 15 LTS ends on 2024-05-18: https://angular.io/guide/releases#actively-supported-versions

We should use this opportunity to upgrade to the latest version of Angular (v17). See https://update.angular.io/ for details

Dependencies:
As discussed in today's DevMtg, this work will be dependent on #2750 , described in more detail at https://wiki.lyrasis.org/display/DSPACE/Migration+to+Standalone+Components

Any work on this upgrade should be based off that PR 2750 because Angular 17 recommends standalone components.

Related Work:
Several past Angular upgrades can be used as a reference, if necessary

• Angular 15 upgrade #2204
• Upgrade to Angular 13 #1567

[tdonohue]

@artlowel: As discussed in today's meeting, assigning this to you for you/your team to work on. Ideally, it'd be good to understand if this is likely to take the (usual) 30-50 hours of effort, or if you anticipate it requiring additional time.

[atarix83]

@artlowel @tdonohue

We shortly analyzed if upgrade to Angular 16 is shorter to do for DSpace 8.0 release.
The main issue is that the view engine is no longer supported

So it means that third party libraries we depend on are no longer supported. Here the current list

• ng2-file-upload -> there is a new version which support Angular 16, so it's not a problem
• ngx-sortablejs -> it's only used by the chips.component so probably we can replace the current implementation by using the angular cdk drag/drop module. Rough estimation 24 hours
• markdown-it-mathjax3 -> we need to find something similar
• angular-idle-preload -> it seems no longer used and probably can be just removed as dependency

[tdonohue]

Regarding markdown-it-mathjax3... a few possible brainstorms

• I've noticed that markdown-it-mathjax3 is really tiny in terms of its unique code (~200 lines of code). That makes me wonder if we could somehow get away with just using markdown-it and MathJax directly? Maybe we can remove this dependency and do it ourselves somehow?
• mathjax-angular claims to support MathJax 3 in Angular 17. It's not a markdown-it plugin though, so we may need to rework the code a bit to support it.

[ybnd]

Something to consider for this upgrade (or the next): Karma is no longer in active development

Angular is moving to Jest and we should too (it's still "experimental" in v16 though)

[saschaszott]

I would prefer upgrading to Angular 17 since

• Angular 16 support ends in almost 6 months (expeced EOL date is 2024-11-08)
• in Angular 17 promises faster builds as Webpack is replaced by more efficient builders (esbuild and Vite)
• Server-Side Rendering improvements (Angular Universal is replaced by @angular/ssr)