fix(flattenObject): flattenObject should retain empty objects and arrays

Author: raon0211

docs/ja/reference/object/flattenObject.md

@@ -107,6 +107,8 @@ const emptyCase = {
 const result = flattenObject(emptyCase);
 console.log(result);
 // {
+//   'empty': {},
+//   'emptyArray: [],
 //   'nullValue': null,
 //   'undefinedValue': undefined
 // }

docs/ko/reference/object/flattenObject.md

@@ -107,6 +107,8 @@ const emptyCase = {
 const result = flattenObject(emptyCase);
 console.log(result);
 // {
+//   'empty': {},
+//   'emptyArray: [],
 //   'nullValue': null,
 //   'undefinedValue': undefined
 // }

docs/reference/object/flattenObject.md

@@ -107,6 +107,8 @@ const emptyCase = {
 const result = flattenObject(emptyCase);
 console.log(result);
 // {
+//   'empty': {},
+//   'emptyArray: [],
 //   'nullValue': null,
 //   'undefinedValue': undefined
 // }

docs/zh_hans/reference/object/flattenObject.md

@@ -107,6 +107,8 @@ const emptyCase = {
 const result = flattenObject(emptyCase);
 console.log(result);
 // {
+//   'empty': {},
+//   'emptyArray: [],
 //   'nullValue': null,
 //   'undefinedValue': undefined
 // }

src/object/flattenObject.spec.ts

@@ -78,6 +78,18 @@ describe('flattenObject', function () {
     });
   });
 
+  it('handles empty arrays correctly', () => {
+    const result = flattenObject({
+      a: {
+        b: [],
+      },
+    });
+
+    expect(result).toEqual({
+      'a.b': [],
+    });
+  });
+
   it('handles `Buffer`s correctly', () => {
     const result = flattenObject({
       a: {

src/object/flattenObject.ts

@@ -53,7 +53,7 @@ function flattenObjectImpl(object: object, prefix: string, delimiter: string): R
       continue;
     }
 
-    if (Array.isArray(value)) {
+    if (Array.isArray(value) && value.length > 0) {
       Object.assign(result, flattenObjectImpl(value, prefixedKey, delimiter));
       continue;
     }