Add ChildItemType, ChildType

Author: phamquyetthang

README.md

@@ -53,6 +53,32 @@ const obj = { foo: { bar: 123, baz: 456 } };
 type NestedKeys = DotNestedKeys<typeof obj>; // "foo.bar" | "foo.baz"
 ```
 
+### ```ChildItemType<T, key>```
+#### Example
+```ts
+  // Example usage
+interface Obj {
+  foo: string[];
+  bar: { baz: number };
+  baz: Array<{id: number, name: string}>;
+}
+type FooItem = ChildItemType<Obj, "foo"> // string
+type BarItem = ChildItemType<Obj, "bar"> // { baz: number }
+type BazItem = ChildItemType<Obj, "baz"> // { id: number, name: string }
+```
+
+### ```ChildType<T, key>```
+#### Example
+```ts
+// Example usage
+interface Obj {
+  foo: string[];
+  bar: { baz: number };
+}
+type FooItem = ChildType<Obj, "foo"> // string[]
+type BarItem = ChildType<Obj, "bar"> // { baz: number }
+```
+
 ## Contributing
 
 Contributions are welcome! If you find any issues or have any suggestions, please open an issue or submit a pull request.

index.ts

@@ -1,5 +1,9 @@
-import { DotNestedKeys } from "./dotNestedKey";
+import { DotNestedKeys } from "./utils/dotNestedKey";
+
+import { ChildItemType, ChildType } from "./utils/childType";
 
 export {
-  DotNestedKeys
-}
+  DotNestedKeys,
+  ChildItemType,
+  ChildType
+}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "ob-scan-ts",
-  "version": "1.0.1",
+  "version": "1.0.2",
   "description": "Nested object to typescript interface",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",

utils/childType.ts

@@ -0,0 +1,41 @@
+/**
+ * The type of the child item.
+ *
+ * @template T - The type of the parent object.
+ * @template key - The key of the child item.
+ * @returns The type of the child item. If the child item is an array, the type of its elements is returned.
+
+ * @example
+ * // Example usage
+ * interface Obj {
+ *   foo: string[];
+ *   bar: { baz: number };
+ *   baz: Array<{id: number, name: string}>;
+ * }
+ *
+ * type FooItem = ChildItemType<Obj, "foo"> // string
+ * type BarItem = ChildItemType<Obj, "bar"> // { baz: number }
+ * type BazItem = ChildItemType<Obj, "baz"> // { id: number, name: string }
+ */
+export type ChildItemType<T, key extends keyof T> = T[key] extends Array<any> ? T[key][number] : T[key];
+
+
+
+/**
+ * The type of the child.
+ *
+ * @template T - The type of the parent object.
+ * @template key - The key of the child item.
+ * @returns The type of the child item. If the child item is an array, the type of its elements is returned.
+ * @example
+ * // Example usage
+ * interface Obj {
+ *   foo: string[];
+ *   bar: { baz: number };
+ * }
+ *
+ * type FooItem = ChildType<Obj, "foo"> // string[]
+ * type BarItem = ChildType<Obj, "bar"> // { baz: number }
+ */
+export type ChildType<T, key extends keyof T> = T[key];
+