Fix convertNullToUndefined (#73)

Author: drebrez

CHANGELOG.md

@@ -15,6 +15,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - UMD build format from Rollup config
 
+### Fixed
+
+- `convertNullToUndefined` is now handling arrays properly
+
 ## [1.5.0] - 2025-07-07
 
 ### Added

src/lib/object.spec.ts

@@ -36,6 +36,12 @@ describe("object tests", () => {
     [{ hello: null }, {}],
     [{ hello: "world", other: null }, { hello: "world" }],
     [{ nested: { prop1: "test", prop2: null } }, { nested: { prop1: "test" } }],
+    [{ nested: [{ prop1: "test", prop2: null }] }, { nested: [{ prop1: "test" }] }],
+    [{ nested: [1, 2, null, 3, 4] }, { nested: [1, 2, undefined, 3, 4] }],
+    [
+      [{ hello: "world" }, null, { nested: { prop1: "test", prop2: null } }],
+      [{ hello: "world" }, undefined, { nested: { prop1: "test" } }],
+    ],
   ])("convertNullToUndefined", (obj, expected) => {
     convertNullToUndefined(obj);
     expect(obj).toStrictEqual(expected);

src/lib/object.ts

@@ -10,16 +10,24 @@ export const isObject = (obj: object): boolean =>
  * Convert null properties to undefined
  * @param obj The object
  */
-export const convertNullToUndefined = (obj: object): void => {
-  if (!isObject(obj)) {
+export const convertNullToUndefined = (obj: object | object[]): void => {
+  if (Array.isArray(obj)) {
+    for (const item of obj as unknown as object[]) {
+      if (item === null) {
+        obj[obj.indexOf(item)] = undefined;
+      } else if (isObject(item)) {
+        convertNullToUndefined(item);
+      }
+    }
+  } else if (!isObject(obj)) {
     return;
   }
 
   for (const key of Object.keys(obj)) {
     const value = obj[key as keyof typeof obj];
     if (value === null) {
       delete obj[key as keyof typeof obj];
-    } else if (isObject(value)) {
+    } else if (isObject(value) || Array.isArray(value)) {
       convertNullToUndefined(value);
     }
   }