Add babel (#10)

Co-authored-by: Luke James <me@luke.gg>

frontend/babel.config.js

@@ -0,0 +1,11 @@
+module.exports = {
+  presets: [
+    [
+      '@babel/preset-env',
+      {
+        useBuiltIns: 'usage',
+        corejs: 3,
+      },
+    ],
+  ],
+}

frontend/package.json

@@ -8,6 +8,9 @@
     "start": "sirv public -s --no-clear --host 0.0.0.0"
   },
   "devDependencies": {
+    "@babel/core": "^7.14.6",
+    "@babel/preset-env": "^7.14.7",
+    "@rollup/plugin-babel": "^5.3.0",
     "@rollup/plugin-commonjs": "^17.0.0",
     "@rollup/plugin-node-resolve": "^11.0.0",
     "@rollup/plugin-replace": "^2.4.2",

frontend/rollup.config.js

@@ -5,6 +5,7 @@ import livereload from 'rollup-plugin-livereload';
 import {terser} from 'rollup-plugin-terser';
 import css from 'rollup-plugin-css-only';
 import replace from "@rollup/plugin-replace";
+import {babel} from '@rollup/plugin-babel';
 
 const production = !process.env.ROLLUP_WATCH;
 
@@ -58,6 +59,11 @@ export default {
             dedupe: ['svelte']
         }),
         commonjs(),
+        babel({
+            babelHelpers: 'bundled',
+            extensions: ['.js', '.mjs', '.html', '.svelte'],
+            include: ['src/**', 'node_modules/svelte/**'],
+        }),
 
         replace({
             env: JSON.stringify({