update to eslint 9

eslint.config.mjs

@@ -0,0 +1,35 @@
+import globals from "globals";
+
+export default [{
+  ignores: ["**/coverage", "**/node_modules"],
+}, {
+  languageOptions: {
+    globals: {
+      ...globals.node,
+    },
+  },
+
+  rules: {
+    "eol-last": "error",
+    eqeqeq: ["error", "allow-null"],
+
+    indent: ["error", 2, {
+      MemberExpression: "off",
+      SwitchCase: 1,
+    }],
+
+    "no-trailing-spaces": "error",
+
+    "no-unused-vars": ["error", {
+      vars: "all",
+      args: "none",
+      caughtErrors: "none",
+      ignoreRestSiblings: true,
+    }],
+
+    "no-restricted-globals": ["error", {
+      name: "Buffer",
+      message: "Use `import { Buffer } from \"node:buffer\"` instead of the global Buffer.",
+    }],
+  },
+}];

package.json

@@ -67,7 +67,7 @@
     "cookie-parser": "1.4.7",
     "cookie-session": "2.1.1",
     "ejs": "^3.1.10",
-    "eslint": "8.47.0",
+    "eslint": "9.39.1",
     "express-session": "^1.18.1",
     "hbs": "4.2.0",
     "marked": "^15.0.3",