chore(eslint-config)!: Update linting rules (#774)

This changes our linting rules to remove eslint-config-next and eslint-config-react since we don't need those in the SDK monorepo. I also added various other linting and made sure we were linting our TypeScript code, which caught a few mistakes but nothing consequential.

This is breaking because we'll need to update code that consumes the linting rules to now pull in the removed configs.

Closes #337

arcjet-next/index.ts

@@ -342,7 +342,7 @@ export function createMiddleware(
     request: NextRequest,
     event: NextFetchEvent,
   ): Promise<NextMiddlewareResult> {
-    let decision = await arcjet.protect(request);
+    const decision = await arcjet.protect(request);
 
     if (decision.isDenied()) {
       // TODO(#222): Content type negotiation using `Accept` header

arcjet/test/index.node.test.ts

@@ -144,7 +144,7 @@ function assertIsLocalRule(rule: ArcjetRule): asserts rule is ArcjetLocalRule {
 function deferred(): [Promise<void>, () => void, (reason?: unknown) => void] {
   let resolve: () => void;
   let reject: (reason?: unknown) => void;
-  let promise = new Promise<void>((res, rej) => {
+  const promise = new Promise<void>((res, rej) => {
     resolve = res;
     reject = rej;
   });

eslint-config/index.js

@@ -1,11 +1,24 @@
 module.exports = {
-  extends: ["next/core-web-vitals", "turbo", "prettier"],
+  extends: [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "turbo",
+    "prettier",
+  ],
   rules: {
-    "@next/next/no-html-link-for-pages": "off",
+    "@typescript-eslint/ban-ts-comment": "off",
+    "@typescript-eslint/ban-types": "off",
+    "@typescript-eslint/no-explicit-any": "off",
+    "@typescript-eslint/no-unused-vars": "off",
+    "no-unused-vars": "off",
+  },
+  parser: "@typescript-eslint/parser",
+  plugins: ["@typescript-eslint"],
+  env: {
+    es2022: true,
   },
   parserOptions: {
-    babelOptions: {
-      presets: [require.resolve("next/babel")],
-    },
+    ecmaVersion: "2022",
+    sourceType: "module",
   },
 };

eslint-config/package.json

@@ -33,14 +33,13 @@
     "lint": "eslint ."
   },
   "dependencies": {
-    "eslint-config-next": "14.2.3",
+    "@typescript-eslint/eslint-plugin": "7.9.0",
+    "@typescript-eslint/parser": "7.9.0",
     "eslint-config-prettier": "9.1.0",
-    "eslint-config-turbo": "1.13.3",
-    "eslint-plugin-react": "7.34.1"
+    "eslint-config-turbo": "1.13.3"
   },
   "peerDependencies": {
-    "eslint": "^8",
-    "next": ">=14"
+    "eslint": "^8"
   },
   "devDependencies": {
     "eslint": "8.57.0"

ip/index.ts

@@ -134,7 +134,7 @@ class Parser {
       let digitCount = 0;
       const hasLeadingZero = p.peakChar() === "0";
 
-      let nextCharAsDigit = () => {
+      function nextCharAsDigit() {
         return p.readAtomically((p) => {
           const c = p.readChar();
           if (c) {
@@ -144,7 +144,7 @@ class Parser {
             }
           }
         });
-      };
+      }
 
       for (
         let digit = nextCharAsDigit();
@@ -205,7 +205,7 @@ class Parser {
         if (i < limit - 1) {
           const ipv4 = p.readSeparator(":", i, (p) => p.readIPv4Address());
           if (isIPv4Tuple(ipv4)) {
-            let [one, two, three, four] = ipv4;
+            const [one, two, three, four] = ipv4;
             groups[i + 0] = u16FromBytes([one, two]);
             groups[i + 1] = u16FromBytes([three, four]);
             return [i + 2, true];

logger/index.ts

@@ -38,9 +38,10 @@ export class Logger {
       case "ERROR":
         this.#logLevel = 3;
         break;
-      default:
+      default: {
         const _exhaustiveCheck: never = levelStr;
         throw new Error(`Unknown log level: ${levelStr}`);
+      }
     }
   }