From 6d1763160bcb545a9f46b2a27b3d11e47ee426d7 Mon Sep 17 00:00:00 2001
From: Chris Garrett <cgarrett@linkedin.com>
Date: Thu, 27 Feb 2020 13:11:55 -0800
Subject: [PATCH] add suggestion

---
 .../-internals/utils/lib/mandatory-setter.ts   | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/packages/@ember/-internals/utils/lib/mandatory-setter.ts b/packages/@ember/-internals/utils/lib/mandatory-setter.ts
index fe9c4b489f4..e23df101b17 100644
--- a/packages/@ember/-internals/utils/lib/mandatory-setter.ts
+++ b/packages/@ember/-internals/utils/lib/mandatory-setter.ts
@@ -14,6 +14,19 @@ export let setWithMandatorySetter:
 
 type PropertyDescriptorWithMeta = PropertyDescriptor & { hadOwnProperty?: boolean };
 
+function isElementKey(key: string | number | symbol) {
+  return typeof key === 'number' ? isPositiveInt(key) : isStringInt(key as string);
+}
+
+function isStringInt(str: string) {
+  let num = parseInt(str, 10);
+  return isPositiveInt(num) && str === String(num);
+}
+
+function isPositiveInt(num: number) {
+  return num >= 0 && num % 1 === 0;
+}
+
 if (DEBUG) {
   let SEEN_TAGS = new WeakSet();
 
@@ -34,9 +47,8 @@ if (DEBUG) {
 
     SEEN_TAGS!.add(tag);
 
-    if (Array.isArray(obj) && !isNaN(Number(keyName))) {
-      // don't setup mandatory setter, arrays can remove property descriptors
-      // themselves and we can't control them correctly.
+    if (Array.isArray(obj) && !isElementKey(keyName)) {
+      // this would replace the conditional
       return;
     }