diff --git a/javascript-practice/src/js/services/commonService.js b/javascript-practice/src/js/services/commonService.js
index 934e78c..ed37218 100644
--- a/javascript-practice/src/js/services/commonService.js
+++ b/javascript-practice/src/js/services/commonService.js
@@ -7,13 +7,23 @@ export default class CommonService {
     this.firebaseService = FirebaseService;
   }
 
+  /**
+   * Connect to Firebase Databse
+   */
   connectToDb() {
     this.firebaseService.reconnect();
   }
 
-  async findKeyByProperty(property, value, path = this.defaultPath) {
+  /**
+   * Find the id of data on database
+   * @param {string} property The property want to get value
+   * @param {string} value The value of property
+   * @param {path} path The path of datbase
+   * @returns {string} The id of data object
+   */
+  async findIdByProperty(property, value, path = this.defaultPath) {
     this.connectToDb();
-    const existUser = this.firebaseService.findKeyByPropery(
+    const existUser = this.firebaseService.findIdByProperty(
       path,
       property,
       value,
@@ -23,6 +33,11 @@ export default class CommonService {
     return result;
   }
 
+  /**
+   * Save data on database
+   * @param {*} data The data wants to save on database
+   * @param {string} path The path of database
+   */
   async save(data, path = this.defaultPath) {
     this.connectToDb();
     const saveUser = this.firebaseService.save(data, path);
@@ -30,11 +45,17 @@ export default class CommonService {
     await timeOutConnect(saveUser);
   }
 
+  /**
+   *
+   * @param {string} id The string of data object
+   * @param {string} path The path of database
+   * @returns {Object || null} Return the object if has, otherwise return null
+   */
   async getDataFromId(id, path = this.defaultPath) {
     this.connectToDb();
     const result = await this.firebaseService.getDataFromId(id, path);
     const data = await timeOutConnect(result);
-    
+
     if (data) return data;
 
     return null;
diff --git a/javascript-practice/src/js/services/firebaseService.js b/javascript-practice/src/js/services/firebaseService.js
index d65b544..9cb2b09 100644
--- a/javascript-practice/src/js/services/firebaseService.js
+++ b/javascript-practice/src/js/services/firebaseService.js
@@ -43,13 +43,13 @@ class FirebaseService {
   }
 
   /**
-   * Find the key of value by property in database
+   * Find id of value by property in database
    * @param {string} path The path of database to be found
    * @param {string} property The property of the value need to be found
    * @param {value} value The value to compare in database
    * @returns {Promise} Return the relsoves when find completed
    */
-  findKeyByPropery(path, property, value) {
+  findIdByProperty(path, property, value) {
     return new Promise((resolve) => {
       onValue(
         ref(this.db, path),
@@ -73,6 +73,12 @@ class FirebaseService {
     });
   }
 
+  /**
+   * Get data object from Id
+   * @param {string} id The id of data object
+   * @param {string} path The path of data save in database
+   * @returns {Promise} Return new Promise
+   */
   getDataFromId(id, path) {
     return new Promise((resolve) => {
       onValue(
diff --git a/javascript-practice/src/js/services/userService.js b/javascript-practice/src/js/services/userService.js
index fa4147f..8ebd00e 100644
--- a/javascript-practice/src/js/services/userService.js
+++ b/javascript-practice/src/js/services/userService.js
@@ -25,7 +25,7 @@ export default class UserService extends CommonService {
    * @returns {Promise || number} Return id user when exist, otherwise will undefined
    */
   getUserIdByEmail(email) {
-    return this.findKeyByProperty('email', email);
+    return this.findIdByProperty('email', email);
   }
 
   /**
diff --git a/javascript-practice/src/js/views/loginView.js b/javascript-practice/src/js/views/loginView.js
index 2ac412e..ab97fce 100644
--- a/javascript-practice/src/js/views/loginView.js
+++ b/javascript-practice/src/js/views/loginView.js
@@ -30,7 +30,7 @@ export default class LoginView extends CommonLoginRegisterView {
    */
   initErrorPopup(content) {
     const typePopup = CONSTANT.TYPE_POPUP.error;
-    const title = 'Error Credential!';
+    const title = 'Error!';
     const btnContent = 'Got it!';
 
     this.initPopupContent(typePopup, title, content, btnContent);
@@ -41,7 +41,8 @@ export default class LoginView extends CommonLoginRegisterView {
 
   /**
    * Add event listener for form input
-   * @param {Function} handler The function need to be set event
+   * @param {Function} getUserByEmail The function need to be set event
+   * @param {Function} createTokenUser The function need to be set event
    */
   addHandlerForm(getUserByEmail, createTokenUser) {
     this.parentElement.addEventListener('submit', (e) => {
@@ -51,6 +52,11 @@ export default class LoginView extends CommonLoginRegisterView {
     });
   }
 
+  /**
+   * The action when submit form
+   * @param {Function} getUserByEmail The function need to be set event
+   * @param {Function} createTokenUser The function need to be set event
+   */
   async submitForm(getUserByEmail, createTokenUser) {
     try {
       // Load spinner
@@ -66,6 +72,7 @@ export default class LoginView extends CommonLoginRegisterView {
         if (userInput.password === user.password) {
           await createTokenUser(user);
           window.location.replace('/');
+
           return;
         }
       }