Reactive Map and Set in Vue - Mini Project: Build & Apply

Reactive Map and Set

📖 Scenario: You are building a simple Vue app to track a collection of favorite fruits and a set of selected fruits. You want to use Vue's reactive Map and Set to keep the UI updated automatically when the data changes.

🎯 Goal: Create a Vue component that uses reactive Map and Set to store fruit names and their colors, and track which fruits are selected. Display the fruits and highlight the selected ones.

📋 What You'll Learn

Create a reactive Map called fruits with exact entries: 'apple' => 'red', 'banana' => 'yellow', 'grape' => 'purple'

Create a reactive Set called selectedFruits initially empty

Add a method toggleSelection that adds a fruit to selectedFruits if not present, or removes it if already selected

Render a list of fruit names with their colors, and highlight the selected fruits with a CSS class

💡 Why This Matters

🌍 Real World

Reactive Map and Set are useful when you want to track collections of data with unique keys or unique items and have the UI update automatically when these collections change.

💼 Career

Understanding reactive collections in Vue helps you build dynamic interfaces that respond instantly to user actions, a common requirement in modern web development jobs.

1

Create reactive Map with fruits and colors

In the <script setup> section, import reactive from 'vue' and create a reactive Map called fruits with these exact entries: 'apple' => 'red', 'banana' => 'yellow', 'grape' => 'purple'.

Vue

import { reactive } from 'vue'

// Create reactive Map called fruits with given entries
// Your code here



  

Hint

Use reactive(new Map([...])) to create a reactive Map with the given fruit-color pairs.

2

Create reactive Set for selected fruits

Below the fruits Map, create a reactive Set called selectedFruits that starts empty.

Vue

import { reactive } from 'vue'

const fruits = reactive(new Map([
  ['apple', 'red'],
  ['banana', 'yellow'],
  ['grape', 'purple']
]))

// Create reactive Set called selectedFruits empty
// Your code here



  

Hint

Use reactive(new Set()) to create an empty reactive Set.

3

Add toggleSelection method to update selectedFruits

Add a function called toggleSelection that takes a fruit name as argument. If selectedFruits has the fruit, remove it; otherwise, add it.

Vue

import { reactive } from 'vue'

const fruits = reactive(new Map([
  ['apple', 'red'],
  ['banana', 'yellow'],
  ['grape', 'purple']
]))

const selectedFruits = reactive(new Set())

// Add toggleSelection function here
// Your code here



  

Hint

Use selectedFruits.has(fruit) to check presence, then delete or add accordingly.

4

Render fruit list with selection highlight

In the <template>, use v-for to loop over fruits.entries(). Display each fruit name and color. Add a class called selected if the fruit is in selectedFruits. Add a @click event on each fruit to call toggleSelection with the fruit name.

Vue

import { reactive } from 'vue'

const fruits = reactive(new Map([
  ['apple', 'red'],
  ['banana', 'yellow'],
  ['grape', 'purple']
]))

const selectedFruits = reactive(new Set())

function toggleSelection(fruit) {
  if (selectedFruits.has(fruit)) {
    selectedFruits.delete(fruit)
  } else {
    selectedFruits.add(fruit)
  }
}



  
  

Hint

Use v-for with fruits.entries(), bind class with selectedFruits.has(fruit), and add @click to call toggleSelection.