MJML comes out of the box with a set of standard components to help you build easily your first templates without having to reinvent the wheel.

For example, an event handler callback that can be used to handle both fullscreenchange and fullscreenerror might look like this:

Yes, you cannot fully express a modern app through templates without sacrificing flexibility and code reusability.

setContext / getContext can only be used once at component init, so how do you share your API result through context? Related: how would you share those API results if the call was made outside of a Svelte component, where setContext would be even more out of the question (and the API call would arguably be better located, for separation of concerns matters)? Well, put a store in your context.

There’s a bunch of fiddly syntax here, not to mention 2 separate build stacks and 3 sets of dependencies, but the end result is awesome. Simply renaming a field on a shared model will reveal all the React components using that value on the front-end, and back-end code using it.

The “shared” schema is effectively the API schema. These are the fields exchanged in the API, common to client and server.

One of the arguments that's frequently deployed in favour of JSX-based frameworks over template-based ones is that JSX allows you to use existing language constructs:

The key to successfully creating reusable components using both render props and scoped slots is being able to correctly separate behavior from presentation. Each time you create a new UI component, think “What is the core behavior of this component? Can I use this anywhere else?”

There are no plans to deprecate the REST API. To reduce the technical burden of supporting two APIs in parallel, they should share implementations as much as possible.

it comes down to opportunities for code reuse. Will your system re-use more code if you use WordPress and its very usable admin area, myriad of available plugins and themes? Or can you re-use more code by harnessing the object-oriented design, DSLs and good software development practices mecca that is Ruby, Rails and the available libraries and tools?