chore(FE-113): create getByPath helper function

src/lib/helper.ts

@@ -27,3 +27,37 @@ export const formatCurrency = (
     maximumFractionDigits,
   }).format(value);
 };
+
+/**
+ * Retrieves a nested value from an object using a dot-delimited key path.
+ * Supports array indexes (e.g., "users.0.name") and returns a default value
+ * if the path does not exist.
+ *
+ * @param obj - The source object to search.
+ * @param path - Dot-delimited key string (e.g., "user.address.city").
+ * @param defaultValue - Optional value to return if the key path is not found.
+ * @returns The value found at the specified path, or the default value.
+ */
+export function getByPath<T, D = undefined>(
+  obj: T,
+  path: string,
+  defaultValue?: D
+): unknown | D {
+  if (obj == null) return defaultValue as D;
+  if (!path) return obj as unknown;
+
+  const segments = path.split('.').filter(Boolean);
+  let cur: { [key: string]: unknown } = obj;
+
+  for (const seg of segments) {
+    if (cur == null) return defaultValue as D;
+    const key: string | number =
+      Array.isArray(cur) && /^\d+$/.test(seg) ? Number(seg) : seg;
+    if (Object(cur) !== cur || !(key in cur)) {
+      return defaultValue as D;
+    }
+    cur = cur[key] as { [key: string]: unknown };
+  }
+
+  return cur as unknown;
+}