Persisting store state in Vue - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the Vuex plugin for persisting state.

Vue

import createPersistedState from '[1]';

Drag options to blanks, or click blank then click option'

Avuex-storage

Bvuex-persist

Cvue-persistedstate

Dvuex-persistedstate

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'vuex-persist' instead of 'vuex-persistedstate'.

Misspelling the package name.

The correct package to import for persisting Vuex store state is vuex-persistedstate.

2fill in blank

medium

Complete the code to add the persisted state plugin to the Vuex store.

Vue

const store = createStore({
  plugins: [[1]()],
  state() {
    return { count: 0 };
  }
});

Drag options to blanks, or click blank then click option'

AcreatePersistedState

BpersistState

CpersistedState

Dpersist

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong plugin name or forgetting to call it as a function.

Passing the plugin without parentheses.

The plugin function imported is called createPersistedState, which needs to be called to create the plugin instance.

3fill in blank

hard

Fix the error in the code to correctly persist only the 'user' module state.

Vue

const store = createStore({
  modules: {
    user: userModule
  },
  plugins: [createPersistedState({
    paths: [[1]]
  })]
});

Drag options to blanks, or click blank then click option'

AuserModule

Buser

C'user'

D'userModule'

Attempts:

3 left

💡 Hint

Common Mistakes

Passing the module variable instead of its name as a string.

Using the module object instead of the string key.

The paths option expects an array of strings representing module names. So the module name 'user' must be a string.

4fill in blank

hard

Fill both blanks to configure the persisted state to use sessionStorage and only save 'settings' module.

Vue

const store = createStore({
  modules: {
    settings: settingsModule
  },
  plugins: [createPersistedState({
    storage: window.[1],
    paths: [[2]]
  })]
});

Drag options to blanks, or click blank then click option'

AsessionStorage

BlocalStorage

C'settings'

D'user'

Attempts:

3 left

💡 Hint

Common Mistakes

Using localStorage instead of sessionStorage.

Passing module variables instead of strings in paths.

To use session storage, set storage to window.sessionStorage. To persist only the 'settings' module, include its name as a string in paths.

5fill in blank

hard

Fill all three blanks to create a persisted state plugin that uses localStorage, saves 'cart' and 'user' modules, and sets a custom key 'myAppStore'.

Vue

const store = createStore({
  modules: {
    cart: cartModule,
    user: userModule
  },
  plugins: [createPersistedState({
    storage: window.[1],
    paths: [[2], [3]],
    key: 'myAppStore'
  })]
});

Drag options to blanks, or click blank then click option'

AlocalStorage

B'cart'

C'user'

D'myAppStore'

Attempts:

3 left

💡 Hint

Common Mistakes

Using sessionStorage instead of localStorage.

Not quoting module names in paths.

Forgetting to set the key or using a wrong key.

Use window.localStorage for storage. The paths array should include the module names as strings: 'cart' and 'user'. The key option sets the storage key, here 'myAppStore'.

Practice

1. What is the main purpose of persisting store state in a Vue application?

easy

A. To speed up the app by caching components

B. To keep the app data saved even after refreshing or closing the browser

C. To automatically update the UI without user input

D. To prevent users from logging out

Solution

1. Step 1: Understand what persisting store state means

   Persisting store state means saving the app's data so it does not disappear when the page reloads or the browser closes.

2. Step 2: Identify the main benefit

   This helps keep user data or app settings intact, improving user experience.

3. Final Answer:

   To keep the app data saved even after refreshing or closing the browser -> Option B

4. Quick Check:

   Persisting state = saving data after refresh [OK]

Hint: Persisting means saving data beyond page reloads [OK]

Common Mistakes:

• Confusing persisting with caching UI components
• Thinking it automatically updates UI without user action
• Believing it prevents user logout directly

2. Which of the following is the correct way to add the vuex-persistedstate plugin to a Vuex store?

easy

A. import createPersistedState from 'vuex-persistedstate';

const store = createStore({
plugins: createPersistedState
});

B. import createPersistedState from 'vuex-persistedstate';

const store = createStore({
persist: createPersistedState()
});

C. import createPersistedState from 'vuex-persistedstate';

const store = createStore({
plugins: [createPersistedState()]
});

D. import createPersistedState from 'vuex-persistedstate';

const store = createStore({
plugins: [createPersistedState]
});

Solution

1. Step 1: Recall the plugin usage syntax

   The vuex-persistedstate plugin is imported as a function and added inside the plugins array when creating the store.

2. Step 2: Check the correct syntax

   import createPersistedState from 'vuex-persistedstate'; const store = createStore({ plugins: [createPersistedState()] }); correctly imports and calls createPersistedState() inside the plugins array.

3. Final Answer:

   import createPersistedState from 'vuex-persistedstate'; const store = createStore({ plugins: [createPersistedState()] }); -> Option C

4. Quick Check:

   Plugin added as function in plugins array [OK]

Hint: Plugins go inside plugins array, called as functions [OK]

Common Mistakes:

• Putting plugin directly as object property instead of in plugins array
• Not calling the plugin function with ()
• Passing plugin without wrapping in array

3. Given this Vuex store setup with vuex-persistedstate:

import { createStore } from 'vuex';
import createPersistedState from 'vuex-persistedstate';

const store = createStore({
  state() {
    return { count: 0 };
  },
  mutations: {
    increment(state) {
      state.count++;
    }
  },
  plugins: [createPersistedState()]
});

store.commit('increment');

// After page reload, what is the value of store.state.count?

medium

A. 1

B. Error

C. undefined

D. 0

Solution

1. Step 1: Understand what happens on commit

   The mutation increment increases count from 0 to 1.

2. Step 2: Effect of vuex-persistedstate plugin

   This plugin saves the state to localStorage, so after page reload, the state is restored with count still 1.

3. Final Answer:

   1 -> Option A

4. Quick Check:

   Persisted state restores count = 1 after reload [OK]

Hint: Persisted state keeps mutations after reload [OK]

Common Mistakes:

• Assuming state resets to initial value after reload
• Thinking plugin does not save mutations
• Confusing undefined or error with normal behavior

4. You added vuex-persistedstate to your Vuex store but the state is not saved after refresh. Which of these is the most likely cause?

medium

A. You forgot to call the plugin function inside the plugins array

B. You did not import Vuex correctly

C. You used mutations instead of actions

D. You did not define the initial state

Solution

1. Step 1: Check plugin usage

   If the plugin is added without calling it as a function (missing parentheses), it won't activate and save state.

2. Step 2: Verify other options

   Importing Vuex correctly, using mutations, and defining initial state are unrelated to plugin activation.

3. Final Answer:

   You forgot to call the plugin function inside the plugins array -> Option A

4. Quick Check:

   Plugin must be called as function to work [OK]

Hint: Always call plugin with () inside plugins array [OK]

Common Mistakes:

• Adding plugin without parentheses
• Blaming mutations or initial state for persistence issues
• Ignoring plugin import errors

5. You want to persist only the user part of your Vuex state and store it in sessionStorage instead of localStorage. Which is the correct way to configure vuex-persistedstate?

hard

A. plugins: [createPersistedState({ only: ['user'], storage: window.sessionStorage })]

B. plugins: [createPersistedState({ paths: ['user'], storage: 'sessionStorage' })]

C. plugins: [createPersistedState({ keys: ['user'], storage: sessionStorage })]

D. plugins: [createPersistedState({ paths: ['user'], storage: window.sessionStorage })]

Solution

1. Step 1: Use the correct option to select parts of state

   The paths option specifies which parts of the state to save, so paths: ['user'] is correct.

2. Step 2: Set storage to sessionStorage correctly

   The storage option expects the storage object, so window.sessionStorage is correct.

3. Final Answer:

   plugins: [createPersistedState({ paths: ['user'], storage: window.sessionStorage })] -> Option D

4. Quick Check:

   Use paths and window.sessionStorage for selective session storage [OK]

Hint: Use paths array and window.sessionStorage for selective session saving [OK]

Common Mistakes:

• Using string 'sessionStorage' instead of window.sessionStorage object
• Using wrong option names like only or keys
• Not specifying paths to limit saved state