From 2d290b295a92f24ebb2836ed314805ea810e2ce7 Mon Sep 17 00:00:00 2001
From: Yosuke Ota <otameshiyo23@gmail.com>
Date: Fri, 22 Jan 2021 09:59:43 +0900
Subject: [PATCH] Fix crash for toLocaleString() in `vue/no-unused-properties`
 rule (#1421)

---
 lib/rules/no-unused-properties.js       |  2 +-
 tests/lib/rules/no-unused-properties.js | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/rules/no-unused-properties.js b/lib/rules/no-unused-properties.js
index 61ac8357f..f89c51878 100644
--- a/lib/rules/no-unused-properties.js
+++ b/lib/rules/no-unused-properties.js
@@ -168,7 +168,7 @@ class UsedProperties {
    */
   constructor(option) {
     /** @type {Record<string, UsedPropertiesTracker[]>} */
-    this.map = {}
+    this.map = Object.create(null)
     /** @type {CallAndParamIndex[]} */
     this.calls = []
     this.unknown = (option && option.unknown) || false
diff --git a/tests/lib/rules/no-unused-properties.js b/tests/lib/rules/no-unused-properties.js
index 89478e06b..eae813bb2 100644
--- a/tests/lib/rules/no-unused-properties.js
+++ b/tests/lib/rules/no-unused-properties.js
@@ -1411,6 +1411,23 @@ tester.run('no-unused-properties', rule, {
         </script>
       `,
       options: deepDataOptions
+    },
+    {
+      filename: 'test.vue',
+      code: `
+      <template>
+        <div> {{ obj.num.toLocaleString() }} </div>
+      </template>
+      <script>
+      export default {
+        data () {
+          return {
+            obj: { num: 42 }
+          }
+        }
+      }
+      </script>`,
+      options: deepDataOptions
     }
   ],