From 46cc6a1511fa707f55f183f840524a969f198310 Mon Sep 17 00:00:00 2001
From: aleclarson <alec.stanford.larson@gmail.com>
Date: Sun, 20 Jan 2019 14:49:19 -0500
Subject: [PATCH] fix(es5): onDelete hook

The `assigned` map cannot be trusted in es5, because of perf optimizations when a patch listener is not used.
---
 src/immer.js | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/immer.js b/src/immer.js
index 46129204..bca73181 100644
--- a/src/immer.js
+++ b/src/immer.js
@@ -4,6 +4,7 @@ import {generatePatches} from "./patches"
 import {
     assign,
     each,
+    has,
     is,
     isDraft,
     isDraftable,
@@ -135,9 +136,18 @@ export class Immer {
             state.finalized = true
             this.finalizeTree(state.draft, path, patches, inversePatches)
             if (this.onDelete) {
-                const {assigned} = state
-                for (const prop in assigned)
-                    assigned[prop] || this.onDelete(state, prop)
+                // The `assigned` object is unreliable with ES5 drafts.
+                if (this.useProxies) {
+                    const {assigned} = state
+                    for (const prop in assigned) {
+                        if (!assigned[prop]) this.onDelete(state, prop)
+                    }
+                } else {
+                    const {base, copy} = state
+                    eachOwn(base, prop => {
+                        if (!has(copy, prop)) this.onDelete(state, prop)
+                    })
+                }
             }
             if (this.onCopy) this.onCopy(state)