HMR - Component Duplicated on Reload

[pfazzino]

Just started testing Parcel using Svelte. Wanted to use HMR so added

if (module.hot) { module.hot.accept() }

to main.js (doesn't matter where I add this) but got the same symptoms as that reported in #31 with output being appended on save. It's not just when editing the main.js though, any save on the svelte component causes the output to be appended.

See example - https://github.com/pfazzino/parcelsveltetest

[benhormann]

if (module.hot) {
  module.hot.dispose(() => {
    app.$destroy();
  });
  module.hot.accept();
}

Credit: figured this out from rixo's templates https://github.com/rixo/svelte-hmr.

[pfazzino]

Yup good fix. This isn't full hmr as state isn't preserved between reloads but it's still a really valuable feature. Is the lack of state preservation a limitation of svelte itself until hmr is officially supported sveltejs/svelte#3632

[benhormann]

Kinda, rixo has got hmr working well enough in webpack / rollup, and even experimenting with snowpack.

Stores are preserved even though component state isn't.