Melte

Svelte compiler for Meteor with built in tracker integration and HMR

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zodern:melte

Build cybernetically enhanced web apps with Meteor and Svelte.

Based on meteor-svelte with these added features:

Tracker statements
Support for hot module replacement (HMR) to update modified components without requiring a full page reload. Requires your app to use Meteor 2 and the hot-module-replacement package.
Handles syntax errors without crashing
Supports Typescript preprocessing for script blocks

Compatible with Meteor 1.8.2 and newer.

Installation

To use meteor-svelte, run the following commands:

meteor add zodern:melte
meteor npm install svelte

The svelte npm package uses newer JS syntax. To fix any errors with the cordova or legacy client, update your package.json file to tell Meteor to recompile it:

{
  ...

  "meteor": {
    ...

    "nodeModules": {
      "recompile": {
        "svelte": ["legacy"]
      }
    }
  }
}

Tracker Statements

In addition to the $ reactive statements Svelte normally supports, this adds $m tracker statements. They behave the same as normal reactive statements, but also rerun whenever any Tracker dependencies they use are invalidated. Behind the scenes, it uses Tracker.autorun.

Example:

<script>
const Todos = new Mongo.Collection('todos');

let sortDirection = 1;

// Tracker will unsubscribe when the Svelte component is destroyed
$m: sub = Meteor.subscribe('todos');
$m: subReady = sub.ready();

// This will rerun whenever the documents are updated or sortDirection is changed
$m: todos = Todos.find({}, { sort: { createdAt: sortDirection}}).fetch()

// You can still use normal reactive statements
$: completedCount = todos.filter(todo => todo.completed).length;
</script>

Sort by:
<select bind:value="{sortDirection}">
  <option value="-1">Oldest First</option>
  <option value="1">Newest First</option>
</select>

{#if !subReady}
  <p>Loading...</p>
{/if}

<ul>
  {#each todos as todo}
    <li>{todo.name} - {todo.createdAt}</li>
  {/each}
</ul>

<p>{completedCount} completed</p>

Typescript

To use typescript with svelte files:

Add the typescript npm package to your app with meteor npm i --save-dev typescript
Add a tsconfig.json file. An example file can be found in the Meteor docs
In your svelte files, set the lang="ts" attribute for scripts:

<script lang="ts">
  let count = 0;

  let doubled: number;
  $: doubled = count * 2;
</script>

<button on:click="{() => count += 1}">Click me</button>
<p>You've clicked the button {count} times (doubled: {doubled}).</p>

Melte does not check the types when compiling Svelte files. To check types, you can use svelte-check or eslint-plugin-svelte3.

Learn more about using Typescript and Svelte from Svelte's docs.

If you encounter the error The "path" argument must be of type string. Received undefined, this is usually from Typescript not being able to find the tsconfig.json file.

Options

Compiler options can be specified with a "svelte:compiler" property in package.json. For example:

{
  ...
  "svelte:compiler": {
    "extensions": ["svelte", "html"],
    "hydratable": true,
    "css": false
  }
}

extensions (default: ["svelte"])

An array of file extensions to be recognized by the package. Note that HTML files are not compiled with the Svelte compiler if they contain top-level <head> or <body> elements. Instead, the contents of the elements are added to the respective sections in the HTML output generated by Meteor (similar to what the static-html package does).

hydratable (default: false)

By default, Svelte removes server-rendered static HTML when the application is loaded on the client and replaces it with a client-rendered version. If you want to reuse (hydrate) server-rendered HTML, set the hydratable option to true (which generates additional code for client components) and use the hydrate option when instantiating your root component.

css (default: true)

Svelte can extract styles for server-side rendering. If you want to render CSS on the server, you might want to set the css option to false so that client-rendered components don't insert CSS into the DOM.

Server-Side Rendering

meteor-svelte supports server-side rendering with minimal configuration. If you import Svelte components on the server, they are automatically built for server-side rendering. See the Svelte API docs, the example app, and the hydratable and css options above for more details.

Examples

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