feat: 🎸 add support for typescript type checking (#37)

* all the wips

* tis working

* feat: 🎸 add support for typescript type checking

* refactor: 💡 better throw message

* fix: 🐛 add formatDiagnostic

* chore: 🤖 prefer type attribute

* Aaaaalmost there

* Filter out valid svelte imports

* refactor: 💡 replace spread with assign.fix getFilenameExtension

* test: 💍 add missing tests for typescript transformer

* refactor: 💡 better nested example

Author: kaisermann

Diff for: examples/svelte-rollup/package-lock.json

@@ -1,12 +1,19 @@
-<template lang="pug">
-	h1 Hello
+<template type="text/pug">
+  h1 Hello!
+  br
+  input(bind:value="{label}")
+  br
+  Nested("{label}")
 </template>
 
-<script>
-	export let name;
+<script type="text/typescript">
+  import Nested from './Nested.svelte'
+  export let label: string = ''
+
+  $: console.log(label)
 </script>
 
-<style lang="stylus">
+<style type="text/stylus">
 	h1
 		color blue
 </style>

Diff for: examples/svelte-rollup/src/App.svelte

@@ -0,0 +1,5 @@
+<script>
+  export let label = ''
+</script>
+
+<div> Your name is '{label}' </div>

Diff for: examples/svelte-rollup/src/Nested.svelte

@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "target": "es2017",
+  },
+  "include": [
+      "./src/**/*"
+  ]
+}