1 files changed, 69 insertions, 0 deletions
diff --git a/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-useless-removeEventListener.js b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-useless-removeEventListener.js
new file mode 100644
index 0000000000..d5f19ab717
--- /dev/null
+++ b/tools/lint/eslint/eslint-plugin-mozilla/lib/rules/no-useless-removeEventListener.js
@@ -0,0 +1,69 @@
+/**
+ * @fileoverview Reject calls to removeEventListenter where {once: true} could
+ *               be used instead.
+ *
+ * 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";
+
+module.exports = {
+  meta: {
+    docs: {
+      url: "https://firefox-source-docs.mozilla.org/code-quality/lint/linters/eslint-plugin-mozilla/rules/no-useless-removeEventListener.html",
+    },
+    messages: {
+      useOnce:
+        "use {once: true} instead of removeEventListener as the first instruction of the listener",
+    },
+    schema: [],
+    type: "suggestion",
+  },
+
+  create(context) {
+    return {
+      CallExpression(node) {
+        let callee = node.callee;
+        if (
+          callee.type !== "MemberExpression" ||
+          callee.property.type !== "Identifier" ||
+          callee.property.name !== "addEventListener" ||
+          node.arguments.length == 4
+        ) {
+          return;
+        }
+
+        let listener = node.arguments[1];
+        if (
+          !listener ||
+          listener.type != "FunctionExpression" ||
+          !listener.body ||
+          listener.body.type != "BlockStatement" ||
+          !listener.body.body.length ||
+          listener.body.body[0].type != "ExpressionStatement" ||
+          listener.body.body[0].expression.type != "CallExpression"
+        ) {
+          return;
+        }
+
+        let call = listener.body.body[0].expression;
+        if (
+          call.callee.type == "MemberExpression" &&
+          call.callee.property.type == "Identifier" &&
+          call.callee.property.name == "removeEventListener" &&
+          ((call.arguments[0].type == "Literal" &&
+            call.arguments[0].value == node.arguments[0].value) ||
+            (call.arguments[0].type == "Identifier" &&
+              call.arguments[0].name == node.arguments[0].name))
+        ) {
+          context.report({
+            node: call,
+            messageId: "useOnce",
+          });
+        }
+      },
+    };
+  },
+};