deepMerge, deepDiff: Fixes for arrays, null-s, undefined-s and __delete* for non-objects

src/util/deepDiff.ts

@@ -1,28 +1,26 @@
-import { unique } from './iteratees';
+import { isLiteralObject, unique } from './iteratees';
 
 const EQUAL = Symbol('EQUAL');
 const DELETE = { __delete: true };
 const DELETE_ALL_CHILDREN = { __deleteAllChildren: true };
 
 export function deepDiff<T extends any>(value1: T, value2: T): Partial<T> | typeof EQUAL | typeof DELETE_ALL_CHILDREN {
-  const type1 = typeof value1;
-  const type2 = typeof value2;
-
   if (value1 === value2) {
     return EQUAL;
   }
 
+  const type1 = typeof value1;
+  const type2 = typeof value2;
+
   if (type1 !== type2) {
     return value2;
   }
 
-  if (type2 !== 'object') {
-    return value2;
+  if (Array.isArray(value1) && Array.isArray(value2) && areSortedArraysDeepEqual(value1, value2)) {
+    return EQUAL;
   }
 
-  if (Array.isArray(value1) && Array.isArray(value2)) {
-    if (areSortedArraysDeepEqual(value1, value2)) return EQUAL;
-
+  if (!isLiteralObject(value1) || !isLiteralObject(value2)) {
     return value2;
   }
 
@@ -38,22 +36,20 @@ export function deepDiff<T extends any>(value1: T, value2: T): Partial<T> | type
   const allKeys = unique(keys1.concat(keys2));
 
   const diff = allKeys.reduce((acc: any, key) => {
-    if (object1[key] === object2[key]) {
-      return acc;
-    }
+    const subValue1 = object1[key];
+    const subValue2 = object2[key];
 
-    const o1has = object1.hasOwnProperty(key);
-    const o2has = object2.hasOwnProperty(key);
-    if (!o2has) {
+    if (!object2.hasOwnProperty(key)) {
       acc[key] = DELETE;
       return acc;
     }
-    if (!o1has && o2has) {
-      acc[key] = object2[key];
+
+    if (!object1!.hasOwnProperty(key)) {
+      acc[key] = subValue2;
       return acc;
     }
 
-    const subDiff = deepDiff(object1[key], object2[key]);
+    const subDiff = deepDiff(subValue1, subValue2);
     if (subDiff !== EQUAL) {
       acc[key] = subDiff;
     }

src/util/deepMerge.ts

@@ -1,41 +1,32 @@
-import { unique } from './iteratees';
-
-export function deepMerge<T extends any>(value1: T, value2: Record<keyof T, any>): T {
-  const type1 = typeof value1;
-  const type2 = typeof value2;
-  if (type1 !== 'object') {
-    return value2 as T;
-  }
-
-  if (Array.isArray(value2)) {
-    return value2 as T;
-  }
-
-  if (type1 !== type2) {
-    return value2 as T;
-  }
+import { isLiteralObject, unique } from './iteratees';
 
+export function deepMerge<T extends any>(value1: T, value2: T): T {
   if (value1 === value2) {
-    return value2 as T;
+    return value2;
   }
 
-  const object1 = value1 as AnyLiteral;
-  const object2 = value2 as AnyLiteral;
+  if (!isLiteralObject(value2)) {
+    return value2;
+  }
+
+  if (!isLiteralObject(value1)) {
+    return reduceDiff(value2) as T;
+  }
 
   // eslint-disable-next-line no-underscore-dangle
-  if (object2.__deleteAllChildren) {
+  if (value2.__deleteAllChildren) {
     return {} as T;
   }
 
-  const allKeys = unique(Object.keys(object1).concat(Object.keys(object2)));
+  const allKeys = unique(Object.keys(value1).concat(Object.keys(value2)));
 
   return allKeys.reduce((acc: AnyLiteral, key) => {
-    const oldValue = object1[key];
+    const oldValue = value1[key];
 
-    if (!(key in object2)) {
+    if (!value2.hasOwnProperty(key)) {
       acc[key] = oldValue;
     } else {
-      const newValue = object2[key];
+      const newValue = value2[key];
       // eslint-disable-next-line no-underscore-dangle
       if (!newValue?.__delete) {
         acc[key] = deepMerge(oldValue, newValue);
@@ -45,3 +36,20 @@ export function deepMerge<T extends any>(value1: T, value2: Record<keyof T, any>
     return acc;
   }, {}) as T;
 }
+
+function reduceDiff(diff: AnyLiteral) {
+  // eslint-disable-next-line no-underscore-dangle
+  if (diff.__deleteAllChildren) {
+    return {};
+  }
+
+  return Object.entries(diff).reduce((acc: AnyLiteral, [key, value]) => {
+    // eslint-disable-next-line no-underscore-dangle
+    if (!value?.__delete) {
+      // eslint-disable-next-line no-null/no-null
+      acc[key] = isLiteralObject(value) ? reduceDiff(value) : value;
+    }
+
+    return acc;
+  }, {});
+}

src/util/iteratees.ts

@@ -188,6 +188,10 @@ export function cloneDeep<T>(value: T): T {
   }, {} as T);
 }
 
+export function isLiteralObject(value: any): value is AnyLiteral {
+  return isObject(value) && !Array.isArray(value);
+}
+
 function isObject(value: any): value is object {
   // eslint-disable-next-line no-null/no-null
   return typeof value === 'object' && value !== null;