fix: ignore key order when comparing objects at max depth

Author: marcolink

src/index.spec.ts

@@ -679,7 +679,7 @@ describe('a generate json patch function', () => {
       },
     };
 
-    it('detects changes as a given depth of 3', () => {
+    it('detects changes at a given depth of 3', () => {
       const patch = generateJSONPatch(before, after, { maxDepth: 3 });
       expect(patch).to.eql([
         {
@@ -737,7 +737,7 @@ describe('a generate json patch function', () => {
       expect(patch).to.eql([]);
     });
 
-    it('detects changes as a given depth of 4', () => {
+    it('detects changes at a given depth of 4', () => {
       const afterModified = structuredClone(after);
       afterModified.firstLevel.secondLevel.thirdLevelTwo = 'hello-world';
       const patch = generateJSONPatch(before, afterModified, { maxDepth: 4 });
@@ -757,7 +757,7 @@ describe('a generate json patch function', () => {
       ]);
     });
 
-    it('detects changes as a given depth of 4 for an array value', () => {
+    it('detects changes at a given depth of 4 for an array value', () => {
       const afterModified = structuredClone(before);
       afterModified.firstLevel.secondLevel.thirdLevelThree = ['test'];
       const patch = generateJSONPatch(before, afterModified, { maxDepth: 4 });
@@ -770,7 +770,7 @@ describe('a generate json patch function', () => {
       ]);
     });
 
-    it('detects changes as a given depth of 4 for an removed array value', () => {
+    it('detects changes as a given depth of 4 for a removed array value', () => {
       const afterModified = structuredClone(before);
       // @ts-ignore
       delete afterModified.firstLevel.secondLevel.thirdLevelThree;
@@ -783,7 +783,7 @@ describe('a generate json patch function', () => {
       ]);
     });
 
-    it('detects changes as a given depth of 4 for an nullyfied array value', () => {
+    it('detects changes as a given depth of 4 for a nullyfied array value', () => {
       const afterModified = structuredClone(before);
       // @ts-ignore
       afterModified.firstLevel.secondLevel.thirdLevelThree = null;
@@ -796,6 +796,33 @@ describe('a generate json patch function', () => {
         },
       ]);
     });
+
+    it('ignores key order on objects when comparing at max depth', () => {
+      const before = {
+        a: {
+          b: {
+            c: {
+              d: 'hello',
+              e: 'world',
+            },
+          },
+        },
+      };
+
+      const after = {
+        a: {
+          b: {
+            c: {
+              e: 'world',
+              d: 'hello',
+            },
+          },
+        },
+      };
+
+      const patch = generateJSONPatch(before, after, { maxDepth: 1 });
+      expect(patch).to.eql([]);
+    });
   });
 });
 

src/index.ts

@@ -198,7 +198,7 @@ export function generateJSONPatch(
       } else if (isJsonObject(rightValue)) {
         if (isJsonObject(leftValue)) {
           if (maxDepthReached(newPath)) {
-            if (JSON.stringify(leftValue) !== JSON.stringify(rightValue)) {
+            if (!deepEqual(leftValue, rightValue)) {
               patch.push({ op: 'replace', path: newPath, value: rightValue });
             }
           } else {
@@ -251,6 +251,29 @@ function isJsonObject(value: JsonValue): value is JsonObject {
   return value?.constructor === Object;
 }
 
+function deepEqual(objA: any, objB: any) {
+  return stringifySorted(objA) === stringifySorted(objB);
+}
+
+function stringifySorted(obj: any): string {
+  if (typeof obj !== 'object' || obj === null) {
+    return JSON.stringify(obj);
+  }
+
+  if (Array.isArray(obj)) {
+    return JSON.stringify(obj.map((item) => stringifySorted(item)));
+  }
+
+  const sortedObj: Record<string, string> = {};
+  const sortedKeys = Object.keys(obj).sort();
+
+  sortedKeys.forEach((key) => {
+    sortedObj[key] = stringifySorted(obj[key]);
+  });
+
+  return JSON.stringify(sortedObj);
+}
+
 export type PathInfoResult = {
   segments: string[];
   length: number;