Handle non-trees gracefully

readme.md

@@ -69,9 +69,9 @@ console.log(newTree);
 
 #### tree
 
-Type: Array or plain object
+Type: Anything
 
-The tree to be copied and modified.
+If it is indeed a tree (i.e. an array or plain object), it will be copied and modified with the shortcut. Otherwise, it will be returned unchanged.
 
 #### shortcutTriggerProp
 
@@ -96,9 +96,10 @@ The name of the new prop to replace the `shortcutTriggerProp` in the parent obje
 
 The `treeShortcut(tree, shortcutTriggerProp, shortcutTargetProp, shortcutName)` will do the following:
 
+* If it is not an array nor a plain object, just return the input. Otherwise:
 * Shallow-clone the `tree` object/array
 * For each (shallow) property in the `tree`:
-    * If its value is not an object (nor an array), do nothing;
+    * If its value is not a plain object (nor an array), do nothing;
     * Otherwise:
         * If its name is `shortcutTriggerProp`:
             * Change the property name to `shortcutName`

source/core.ts

@@ -57,7 +57,7 @@ function treeShortcutHelper(tree: any, from: string, to: string, name: string):
 }
 
 export function treeShortcut<
-	Tree extends AnyArray | AnyPlainObject,
+	Tree,
 	ShortcutTriggerProp extends string,
 	ShortcutTargetProp extends string,
 	ShortcutName extends string,

test/test.ts

@@ -183,3 +183,26 @@ test('Does not mess with non-plain objects', t => {
 		expected,
 	);
 });
+
+test('Leaves non-trees untouched', t => {
+	expectTypeOf<TreeShortcut<Date, 'foo', 'bar', 'baz'>>()
+		.toEqualTypeOf<Date>();
+
+	expectTypeOf<TreeShortcut<number, 'foo', 'bar', 'baz'>>()
+		.toEqualTypeOf<number>();
+
+	expectTypeOf<TreeShortcut<null, 'foo', 'bar', 'baz'>>()
+		.toEqualTypeOf<null>();
+
+	expectTypeOf<TreeShortcut<undefined, 'foo', 'bar', 'baz'>>()
+		.toEqualTypeOf<undefined>();
+
+	const date = new Date();
+	t.is(treeShortcut(date, 'a', 'b', 'c'), date);
+
+	t.is(treeShortcut(true, 'a', 'b', 'c'), true);
+	t.is(treeShortcut(null, 'a', 'b', 'c'), null);
+	t.is(treeShortcut(undefined, 'a', 'b', 'c'), undefined);
+	t.is(treeShortcut(0, 'a', 'b', 'c'), 0);
+	t.is(treeShortcut('hello', 'a', 'b', 'c'), 'hello');
+});