From ad26c818556650b4aff9d1de60fc0b54f6b43cc6 Mon Sep 17 00:00:00 2001
From: Jennings Zhang <jenni_zh@protonmail.com>
Date: Fri, 23 Feb 2024 14:32:48 -0500
Subject: [PATCH] Use fast-deep-equal

---
 package.json   |  3 +++
 pnpm-lock.yaml |  7 +++++++
 src/diff.ts    | 21 +++------------------
 3 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/package.json b/package.json
index c7054b4..73d5e9c 100644
--- a/package.json
+++ b/package.json
@@ -31,5 +31,8 @@
     "@niivue/niivue": "^0.39.0",
     "react": "^17 || ^18",
     "typescript": "^5.0.0"
+  },
+  "dependencies": {
+    "fast-deep-equal": "^3.1.3"
   }
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 4a1d03c..535c8ac 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -5,6 +5,9 @@ settings:
   excludeLinksFromLockfile: false
 
 dependencies:
+  fast-deep-equal:
+    specifier: ^3.1.3
+    version: 3.1.3
   react:
     specifier: ^17 || ^18
     version: 18.2.0
@@ -922,6 +925,10 @@ packages:
       strip-final-newline: 3.0.0
     dev: true
 
+  /fast-deep-equal@3.1.3:
+    resolution: {integrity: sha512-f3qQ9oQy9j2AhBe/H9VC91wLmKBCCU/gDOnKNAYG5hswO7BLKj09Hc5HYNz9cGI++xlpDCIgDaitVs03ATR84Q==}
+    dev: false
+
   /fflate@0.7.4:
     resolution: {integrity: sha512-5u2V/CDW15QM1XbbgS+0DfPxVB+jUKhWEKuuFuHncbk3tEEqzmoXL+2KyOFuKGqOnmdIy0/davWF1CkuwtibCw==}
     dev: true
diff --git a/src/diff.ts b/src/diff.ts
index 17c099b..11ece71 100644
--- a/src/diff.ts
+++ b/src/diff.ts
@@ -1,4 +1,5 @@
-import { HasUrlObject } from "./model.ts";
+import { HasUrlObject } from "./model";
+import equal from "fast-deep-equal/es6";
 
 /**
  * A special value which indicates that the difference between two objects is Irreconcilable.
@@ -186,7 +187,7 @@ function diffPrimitive<T extends { [key: string]: any }>(
   const yKeys = Object.keys(y);
   const deletedKeys = setDifference(xKeys, yKeys);
   const addedKeys = setDifference(yKeys, xKeys);
-  const changedKeys = xKeys.filter((key) => !deepishEqual(x[key], y[key]));
+  const changedKeys = xKeys.filter((key) => !equal(x[key], y[key]));
   const diffKeys = addedKeys.concat(changedKeys);
   return {
     ...Object.fromEntries(deletedKeys.map((key) => [key, undefined])),
@@ -194,22 +195,6 @@ function diffPrimitive<T extends { [key: string]: any }>(
   };
 }
 
-/**
- * Equality for arrays and primitives.
- */
-function deepishEqual<T>(x: T, y: T): boolean {
-  if (Array.isArray(x)) {
-    if (!Array.isArray(y)) {
-      return false;
-    }
-    return zipArrays(x, y).reduce(
-      (same, [a, b]) => same && deepishEqual(a, b),
-      true,
-    );
-  }
-  return x === y;
-}
-
 function zipArrays<X, Y>(x: X[], y: Y[]): [X, Y][] {
   return x.map((v, i) => [v, y[i]]);
 }