Move rollup config to ESM

package.json

@@ -4,7 +4,7 @@
   "version": "1.23.3",
   "license": "MIT",
   "scripts": {
-    "build": "rollup --config rollup.config.js",
+    "build": "rollup --config rollup.config.mjs",
     "docs:clean": "cd docs/api; make clean-all",
     "docs:install": "cd docs/api; pip install -r requirements.txt",
     "docs:build": "typedoc && cd docs/api && make html dist",

rollup.config.mjs

@@ -0,0 +1,56 @@
+// The following is only possible from Node 18 onwards
+// import pkg from "./package.json" assert { type: "json" };
+
+// Until we only support Node 18+, this should be used instead
+// (see https://rollupjs.org/guide/en/#importing-packagejson) 
+import { createRequire } from 'node:module';
+const require = createRequire(import.meta.url);
+const pkg = require('./package.json');
+
+import typescript from "rollup-plugin-typescript2";
+
+export default {
+  input: "./src/index.ts",
+  output: [
+    {
+      file: pkg.main,
+      format: "cjs",
+    },
+    {
+      file: pkg.module,
+      entryFileNames: "[name].es.js",
+      format: "esm",
+    },
+    {
+      dir: "dist",
+      entryFileNames: "[name].mjs",
+      format: "esm",
+      preserveModules: true,
+    },
+    {
+      dir: "umd",
+      format: "umd",
+      name: "SolidClient",
+    },
+  ],
+  plugins: [
+    typescript({
+      // Use our own version of TypeScript, rather than the one bundled with the plugin:
+      typescript: require("typescript"),
+      tsconfigOverride: {
+        // Exclude tests:
+        exclude: ["**/*.test.ts"],
+        compilerOptions: {
+          module: "esnext",
+        },
+      },
+    }),
+  ],
+  external: [
+    "cross-fetch",
+    "http-link-header",
+    "@rdfjs/dataset",
+    "n3",
+    "jsonld",
+  ],
+};