1 files changed, 34 insertions, 0 deletions
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/var-only-at-top-level.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/var-only-at-top-level.js
new file mode 100644
index 000000000..a1e14e166
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/var-only-at-top-level.js
@@ -0,0 +1,34 @@
+/**
+ * @fileoverview Marks all var declarations that are not at the top level
+ *               invalid.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+"use strict";
+
+// -----------------------------------------------------------------------------
+// Rule Definition
+// -----------------------------------------------------------------------------
+
+var helpers = require("../helpers");
+
+module.exports = function(context) {
+  // ---------------------------------------------------------------------------
+  // Public
+  //  --------------------------------------------------------------------------
+
+  return {
+    "VariableDeclaration": function(node) {
+      if (node.kind === "var") {
+        if (helpers.getIsGlobalScope(context.getAncestors())) {
+          return;
+        }
+
+        context.report(node, "Unexpected var, use let or const instead.");
+      }
+    }
+  };
+};