Merge pull request #12 from aloisklink/fix-esm-imports

Add a basic `eslint` linter config, and fixes some bugs that it caught

.eslintrc.cjs

@@ -0,0 +1,24 @@
+module.exports = {
+  env: {
+    browser: true,
+    es6: true, // todo, increase this es2016 or later to use new Javascript features
+    node: true,
+  },
+  extends: ['eslint:recommended', 'plugin:import/recommended'],
+  overrides: [],
+  parserOptions: {
+    sourceType: 'module',
+  },
+  rules: {
+    // make sure that all files have an extension (required by ESM)
+    'import/extensions': [
+      'error',
+      'always',
+      {
+        js: 'always',
+        jsx: 'never',
+        mjs: 'always',
+      },
+    ],
+  },
+};

.github/workflows/test.yml

@@ -19,5 +19,7 @@ jobs:
           node-version: ${{ matrix.node-version }}
           cache: 'npm'
       - run: npm ci # throws an error if the package-lock.json file is out of sync
+      - name: Check for linting errors (run `npm run lint:fix` to fix)
+        run: npm run lint
       - name: Check for prettier errors (run `npm run format` to fix)
         run: npx prettier --check .