diff --git a/src/common/helper/page.helper.ts b/src/common/helper/page.helper.ts
index 18946f12..ad63d8ea 100644
--- a/src/common/helper/page.helper.ts
+++ b/src/common/helper/page.helper.ts
@@ -1,6 +1,6 @@
 /*
  *  Description: This file implements the PageHelper class.
- *               Its an utility class for generating the PageResponseDto data.
+ *               It's a utility class for generating the PageResponseDto data.
  *
  *  Author(s):
  *      Nictheboy Li    <nictheboy@outlook.com>
@@ -10,15 +10,22 @@
 import { PageDto } from '../DTO/page-response.dto';
 
 export class PageHelper {
-  // Used when you do
-  //
-  // SELECT ... FROM ...
-  //   WHERE ...
-  //   AND id >= (firstId)
-  // LIMIT (pageSize + 1)
-  // ORDER BY id ASC
-  //
-  // in SQL.
+  /**
+   * Used to paginate data from the starting position.
+   * Typically used for the initial query to paginate data.
+   *
+   * Equivalent SQL:
+   * SELECT ... FROM ...
+   * WHERE ...
+   * AND id >= (firstId)
+   * LIMIT (pageSize + 1)
+   * ORDER BY id ASC
+   *
+   * @param data Array of data items
+   * @param pageSize Number of items per page
+   * @param idGetter Function to get the ID of a data item
+   * @returns A tuple containing the paginated data array and pagination information
+   */
   static PageStart<TData>(
     data: TData[],
     pageSize: number,
@@ -27,23 +34,31 @@ export class PageHelper {
     return PageHelper.PageInternal(data, pageSize, false, 0, idGetter);
   }
 
-  // Used when you do both
-  //
-  // SELECT ... FROM ...
-  //   WHERE ...
-  //   AND id < (firstId)
-  // LIMIT (pageSize)
-  // ORDER BY id DESC
-  //
-  // and
-  //
-  // SELECT ... FROM ...
-  //   WHERE ...
-  //   AND id >= (firstId)
-  // LIMIT (pageSize + 1)
-  // ORDER BY id ASC
-  //
-  // in SQL.
+  /**
+   * Used to paginate data from a middle position.
+   * Handles both previous and current page data.
+   *
+   * Equivalent SQL for fetching the previous page:
+   * SELECT ... FROM ...
+   * WHERE ...
+   * AND id < (firstId)
+   * LIMIT (pageSize)
+   * ORDER BY id DESC
+   *
+   * Equivalent SQL for fetching the current page:
+   * SELECT ... FROM ...
+   * WHERE ...
+   * AND id >= (firstId)
+   * LIMIT (pageSize + 1)
+   * ORDER BY id ASC
+   *
+   * @param prev Array of data items from the previous page
+   * @param data Array of data items from the current page
+   * @param pageSize Number of items per page
+   * @param idGetterPrev Function to get the ID of a data item from the previous page
+   * @param idGetter Function to get the ID of a data item from the current page
+   * @returns A tuple containing the paginated data array and pagination information
+   */
   static PageMiddle<TPrev, TData>(
     prev: TPrev[],
     data: TData[],
@@ -67,14 +82,22 @@ export class PageHelper {
     );
   }
 
-  // Used when you do
-  //
-  // SELECT ... FROM ...
-  //   WHERE ...
-  // LIMIT 1000
-  // ORDER BY id ASC
-  //
-  // in SQL.
+  /**
+   * Used to paginate data from a complete dataset.
+   * This method should be used only when the entire dataset is loaded into memory.
+   * Determines the starting point for pagination based on the provided pageStart parameter.
+   *
+   * This method handles two scenarios:
+   * 1. When pageStart is undefined, it starts pagination from the beginning of the dataset.
+   * 2. When pageStart is defined, it starts pagination from the specified ID.
+   *
+   * @param allData Array of all data items
+   * @param pageStart The ID where pagination starts
+   * @param pageSize Number of items per page
+   * @param idGetter Function to get the ID of a data item
+   * @param errorIfNotFound Optional error handler function, called if pageStart is not found in allData
+   * @returns A tuple containing the paginated data array and pagination information
+   */
   static PageFromAll<TData>(
     allData: TData[],
     pageStart: number | undefined,
@@ -92,7 +115,6 @@ export class PageHelper {
       const pageStartIndex = allData.findIndex((r) => idGetter(r) == pageStart);
       if (pageStartIndex == -1) {
         /* istanbul ignore if  */
-        // Above is a hint for istanbul to ignore this if-statement.
         if (errorIfNotFound == undefined)
           return this.PageStart([], pageSize, idGetter);
         else errorIfNotFound(pageStart);
@@ -103,6 +125,16 @@ export class PageHelper {
     }
   }
 
+  /**
+   * Internal method used to handle the core pagination logic.
+   *
+   * @param data Array of data items
+   * @param pageSize Number of items per page
+   * @param hasPrev Whether there is a previous page
+   * @param prevStart The starting ID of the previous page
+   * @param idGetter Function to get the ID of a data item
+   * @returns A tuple containing the paginated data array and pagination information
+   */
   private static PageInternal<TData>(
     data: TData[],
     pageSize: number,