Default eslint config (w3c#72)

* First pass on default linting config

* Change 'no-empty' to 'warn' in eslint config

Author: stalgiag

eslint.config.js

@@ -1,6 +1,22 @@
 import globals from 'globals';
+import js from '@eslint/js';
+import eslintConfigEslint from 'eslint-config-eslint';
 
 export default [
-  { files: ['**/*.{js,mjs,cjs}'] },
-  { languageOptions: { globals: { ...globals.browser, ...globals.node } } },
+  js.configs.recommended,
+  {
+    files: ['**/*.{js,mjs,cjs}'],
+    languageOptions: {
+      globals: {
+        ...globals.browser,
+        ...globals.node,
+      },
+    },
+    rules: {
+      ...eslintConfigEslint.rules,
+      // TODO: Remove these exceptions once TypeScript conversion happens
+      'no-empty': 'warn',
+      'no-unused-vars': 'warn',
+    },
+  },
 ];