chore: add Svelte entry point to exports map

Closes #307

scripts/npm-package.js

@@ -15,6 +15,7 @@ async function npmPackage() {
  // Copy source folder to package
  mkdir("./package/src");
  fs.cpSync("./src", "./package", { recursive: true });
+ fs.rmSync("./package/src", { recursive: true, force: true });
 
  const pkgJson = JSON.parse(
  fs.readFileSync("./package/package.json", "utf-8"),
@@ -23,21 +24,46 @@ async function npmPackage() {
  delete pkgJson.scripts;
  delete pkgJson.devDependencies;
 
- pkgJson.svelte = "./index.js";
- pkgJson.types = "./index.d.ts";
- pkgJson.sideEffects = ["src/styles/*.css"];
-
- pkgJson.exports = {};
+ pkgJson.exports = {
+   ".": {
+  svelte: "./index.js",
+ },
+ };
 
  const deny_list = new Set(["LICENSE", "README.md"]);
 
+ /** {@link pkgJson.exports} already accounts for the Svelte entry point. */
+ const skip_list = new Set(["index.js"]);
+
  await totalist("./package", (rel, abs, stats) => {
  if (stats.isFile() && !rel.endsWith(".d.ts") && !deny_list.has(rel)) {
+ if (skip_list.has(rel)) return;
+
+ if (/\//g.test(rel)) {
+ // Skip files inside of folders. A subpath is more readable.
+ return;
+ }
+
  const rel_prefix = "./" + rel;
- pkgJson.exports[rel_prefix.replace(/\.js$/, "")] = rel_prefix;
+
+ // Remove file extension for JS files as it is the default.
+ const exports_key = rel_prefix.replace(/\.js$/, "");
+
+ pkgJson.exports[exports_key] = rel_prefix;
  }
  });
 
+ pkgJson.exports["./styles/*"] = "./styles/*";
+ pkgJson.exports["./languages/*"] = "./languages/*";
+
+ // Svelte entry point is deprecated but we preserve it for backwards compatibility.
+ pkgJson.svelte = "./index.js";
+ pkgJson.types = "./index.d.ts";
+
+ // Most modern bundlers know if standalone StyleSheets are used.
+ // We specify it here to be sure so that it will not be mistakenly tree-shaken.
+ pkgJson.sideEffects = ["src/styles/*.css"];
+
  await writeFile("./package/package.json", JSON.stringify(pkgJson, null, 2));
  console.timeEnd("package");
 }