Components: MomentJS cannot be optimized and the moment-date-adapter is causing increased bundle size

[realharry]

Reproduction

Steps to reproduce:

1. Add a dependency on MatMomentDateModule on your angular app.
2. Build the app with ng build --prod.
3. Notice the increase in the output bundle size.

Screenshot of webpack-bundle-analyzer of the main bundle (built with --stats-json):

Expected Behavior

Addition of a "simple" widget should not increase the output bundle size dramatically.

Actual Behavior

Huge increase in the bundle size, on the order of a few hundred kilobytes. (Over 338kb added by moment.js alone, in my example.)

Environment

• Angular: 9.0.4
• CDK/Material: 9.1.0
• Browser(s): N/A
• Operating System (e.g. Windows, macOS, Ubuntu): N/A

[marko164]

It would be great if MatMomentDateAdapter could work with moment-mini

[eduardocereto]

moment.js unfortunately doesn't do well with tree shaking. Here are some extra info on alternatives that do.

https://github.com/you-dont-need/You-Dont-Need-Momentjs

[devversion]

Thanks for this issue. We are aware of the limitations with MomentJS. We should really document the bundle size implications with the moment date adapter. Additionally it might be good to provide a better integrated date adapter (one that can be more optimized).

We have various proposals for other date adapters (such as date-fns or day.js)

[Splaktar]

Related feature request for date-fns Adapter: https://github.com/angular/components/issues/10278. PRs wanted for this.

[jelbourn]

Tracking providing official alternatives to moment in #20599

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