Svelte 5 about melte HOT 4 OPEN

// tracker.svelte.js inside zodern:melte
import { Tracker } from 'meteor/tracker';
import { onDestroy } from 'svelte';

export const track = (reactive) => { // reactive is a reactive data source, e.g. a cursor or a value like Meteor.user()
  const isCursor = reactive instanceof Meteor.Collection.Cursor;
  let data = isCursor ? $state([]) : $state(undefined);
  let handle;

  if (isCursor) { // allows for fine-grained updates
    handle = reactive.observe({
      added: (document) => data.push(document),
      changed: (newDocument, oldDocument) => data[data.findIndex((item) => item._id === oldDocument._id)] = newDocument,
      removed: (oldDocument) => data.splice(data.findIndex((item) => item._id === oldDocument._id), 1)
    });
  } else {
    handle = Tracker.autorun(() => {
      data = reactive
    })
  }
   
  onDestroy(() => handle.stop());

  return data;
};

export const subscribe = (subscriptionName, ...args) => {
  let sub = $state({ ready: false })

  const handle = Meteor.subscribe(subscriptionName, …args, onReady(() => {
    sub.ready = true
  });
 
  onDestroy(() => handle.stop());

  return sub;
};

// store.js
import { track } from 'meteor/zodern:melte'

export const currentUser = track(Meteor.user())

// App.svelte
 <script>
  import { track, subscribe } from 'meteor/zodern:melte'

  const sub = subscribe('todos');
  const todos = track(Todos.find());

  async function createTodo(event) {
    event.preventDefault();
    // call your Meteor method
  }
</script>

{#if !sub.ready}
  <p>loading…</p>
{/if}

{#if currentUser}
  <form onsubmit={createTodo}>
    <input type=‘text’ placeholder=‘Type to add new todos’ />
  </form>
{/if}

{#each todos as todo (todo._id)}
  <p>{todo.text}</p>
{/each}