migrate eslint to v9

eslint.config.cjs

@@ -0,0 +1,52 @@
+const globals = require("globals");
+const js = require("@eslint/js");
+
+const {
+	FlatCompat,
+} = require("@eslint/eslintrc");
+
+const compat = new FlatCompat({
+	baseDirectory: __dirname,
+	recommendedConfig: js.configs.recommended,
+	allConfig: js.configs.all
+});
+
+module.exports = [{
+	ignores: ["**/.eslintrc.js", "admin/words.js"],
+}, ...compat.extends("eslint:recommended"), {
+	plugins: {},
+
+	languageOptions: {
+		globals: {
+			...globals.node,
+			...globals.mocha,
+		},
+
+		ecmaVersion: 2020,
+		sourceType: "commonjs",
+	},
+
+	rules: {
+		indent: ["error", "tab", {
+			SwitchCase: 1,
+		}],
+
+		"no-console": "off",
+
+		"no-unused-vars": ["error", {
+			ignoreRestSiblings: true,
+			argsIgnorePattern: "^_",
+		}],
+
+		"no-var": "error",
+		"no-trailing-spaces": "error",
+		"prefer-const": "error",
+
+		quotes: ["error", "double", {
+			avoidEscape: true,
+			allowTemplateLiterals: true,
+		}],
+
+		semi: ["error", "always"],
+	},
+}];