ESLint 9 (#489)

* upgrades eslint to v9, with plugins

* make eslint work and builds

* small adjustments to fix tests and such

* mmmmmm... js

Author: bkendall

.eslintignore

@@ -0,0 +1,78 @@
+import eslint from "@eslint/js";
+import eslintConfigGoogle from "eslint-config-google";
+import eslintConfigPrettier from "eslint-config-prettier";
+import eslintConfigJSDoc from "eslint-plugin-jsdoc";
+import eslintPluginPrettierRecommended from "eslint-plugin-prettier/recommended";
+import tseslint from "typescript-eslint";
+import globals from "globals";
+
+export default [
+  eslint.configs.recommended,
+  ...tseslint.configs.recommendedTypeChecked,
+  ...tseslint.configs.stylisticTypeChecked,
+  eslintConfigJSDoc.configs["flat/recommended"],
+  eslintConfigGoogle,
+  eslintConfigPrettier,
+  eslintPluginPrettierRecommended,
+  {
+    ignores: ["eslint.config.mjs", "lib/**/*", "coverage/**/*"],
+  },
+  {
+    rules: {
+      "jsdoc/newline-after-description": "off",
+      "jsdoc/require-jsdoc": ["warn", { publicOnly: true }],
+      "jsdoc/require-param-type": "off",
+      "jsdoc/require-returns-type": "off",
+
+      "@typescript-eslint/no-require-imports": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unused-expressions": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unused-vars": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/prefer-includes": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/prefer-optional-chain": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/prefer-promise-reject-errors": "warn", // TODO(bkendall): remove allow to error.
+
+      "no-unused-vars": "off", // Turned off in favor of @typescript-eslint/no-unused-vars.
+      "require-atomic-updates": "off", // This rule is so noisy and isn't useful: https://github.com/eslint/eslint/issues/11899
+      "require-jsdoc": "off", // This rule is deprecated and superseded by jsdoc/require-jsdoc.
+      "valid-jsdoc": "off", // This is deprecated but included in recommended configs.
+    },
+    languageOptions: {
+      ecmaVersion: 2020,
+      globals: {
+        ...globals.node,
+        ...globals.mocha,
+      },
+      parserOptions: {
+        ecmaVersion: "es2020",
+        projectService: {
+          project: "./tsconfig.json",
+          allowDefaultProject: ["eslint.config.js"],
+        },
+        tsconfigRootDir: import.meta.dirname,
+      },
+    },
+  },
+  {
+    files: ["**/*.ts"],
+    rules: {
+      "@typescript-eslint/no-explicit-any": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-argument": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-assignment": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-call": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-member-access": "warn", // TODO(bkendall): remove allow to error.
+    },
+  },
+  {
+    files: ["**/*.js"],
+    rules: {
+      "@typescript-eslint/no-this-alias": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-argument": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-assignment": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-call": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-member-access": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-unsafe-return": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/no-var-requires": "warn", // TODO(bkendall): remove allow to error.
+      "@typescript-eslint/unbound-method": "warn", // TODO(bkendall): remove allow to error.
+    },
+  },
+];