When merging config, union arrays instead of replacing them.

Changelog.md

@@ -1,3 +1,6 @@
+## 1.0.3 / 2024-05-30
+* When merging config, union arrays (instead of right replacing left).
+
 ## 1.0.2 / 2024-05-27 (No functional changes)
 * Improve index.ts
 

README.md

@@ -151,11 +151,15 @@ See `discoverInitializers` and `invokeInitializers` for more info.
 
 ## Implementation Notes
 lodash.merge is used for configuration merging (along with lodash.set if you are merging at a key prefixed merge point).  
-Understanding how lodash.merge actually works is important, so please read [its documentation](https://lodash.com/docs/#merge).  Once you understand it,
-you will see a problem...
-* How do I replace an object or an array of values?
-
-This library actually uses [lodash.mergeWith](https://lodash.com/docs/#mergeWith) in order to implement a "not" ability (aka `!`, aka _bang_, aka _replacement_).  
+Understanding how lodash.merge actually works is important, so please read [its documentation](https://lodash.com/docs/#merge).  
+Once you understand it,
+you will see a problem that this library uses  [lodash.mergeWith](https://lodash.com/docs/#mergeWith) to address...
+* How do I merge two arrays (instead of having the left array replaced by the right).
+* How do I replace an object (as opposed to merging it)?
+
+To address the first, we use lodash.union to 'merge' arrays which is (IMO) the intuitive behavior. 
+If you really did want to replace the left arry with the right, you can us the 'not' feature described next.  
+To address the second, we implement a "not" ability (aka `!`, aka _bang_, aka _replacement_).  
 This feature allows you to **overwrite** a node in the hierarchy instead of merging.
 ```json5
 // Merging in this json5 override will "merge" the values into configuration,

package.json

@@ -1,6 +1,6 @@
 {
 	"name": "dyflex-config",
-	"version": "1.0.2",
+	"version": "1.0.3",
 	"description": "Simple, dynamic, flexible, configuration library.",
 	"author": "Frank Stock",
 	"license": "MIT",

src/merge-config.ts

@@ -1,4 +1,4 @@
-import {get as lodashGet, mergeWith as lodashMergeWith, set as lodashSet} from 'lodash';
+import {get as lodashGet, mergeWith as lodashMergeWith, set as lodashSet, union as lodashUniton} from 'lodash';
 
 /**
  * A unique marker used as the default value for lodashGet.
@@ -33,6 +33,8 @@ export function mergeConfig<T extends object>(dst: T, src: object, mergePoint?:
 			});
 			object[key.substring(1)] = srcValue;
 		}
+		else if (Array.isArray(objValue))
+			return lodashUniton(objValue, srcValue);
 		return undefined;
 	});
 	deletes.forEach(d => d());