Once you've written the imperative library/util code once, your components are super slim and completely reactive/declarative. Wow.

Svelte's advantage here is that it indicates the need for an update at the place where the associated data is updated, instead of at each place the data is used. Then each template expression of reactive statement is able to check very quickly if it needs to rerender or not.

So how do we declare the variable y to be the value of x plus 5? That's where reactive programming comes in. Reactive programming is a way of programming that makes it possible solve this problem

reactions bridge reactive and imperative programming