Migrate to flatconfig

webextensions/Makefile

@@ -9,7 +9,7 @@ install_dependency:
 	[ -e "$(NPM_BIN_DIR)/eslint" -a -e "$(NPM_BIN_DIR)/jsonlint-cli" ] || npm install
 
 lint: install_dependency
-	"$(NPM_BIN_DIR)/eslint" . --ext=.js --report-unused-disable-directives
+	"$(NPM_BIN_DIR)/eslint" . --report-unused-disable-directives
 	find . -type d -name node_modules -prune -o -type f -name '*.json' -print | xargs "$(NPM_BIN_DIR)/jsonlint-cli"
 
 format: install_dependency

webextensions/eslint.config.mjs

@@ -0,0 +1,52 @@
+import globals from "globals";
+
+export default [{
+    ignores: ["eslint.config.mjs", "extlib/*", "!**/.eslintrc.js"],
+}, {
+    languageOptions: {
+        globals: {
+            ...globals.browser,
+            ...globals.webextensions,
+        },
+
+        ecmaVersion: 2022,
+        sourceType: "script",
+    },
+
+    settings: {
+        "import/resolver": {
+            "babel-module": {
+                root: ["./"],
+            },
+        },
+    },
+
+    rules: {
+        "no-const-assign": "error",
+
+        "prefer-const": ["warn", {
+            destructuring: "any",
+            ignoreReadBeforeAssign: false,
+        }],
+
+        indent: ["warn", 2, {
+            SwitchCase: 1,
+            MemberExpression: 1,
+
+            CallExpression: {
+                arguments: "first",
+            },
+
+            VariableDeclarator: {
+                var: 2,
+                let: 2,
+                const: 3,
+            },
+        }],
+
+        quotes: ["warn", "single", {
+            avoidEscape: true,
+            allowTemplateLiterals: true,
+        }],
+    },
+}];