Applying Maps to Real-World Challenges in JavaScript

Introduction and Goal Setting

Hello there! In this lesson, we will apply Maps to real-world challenges. Our focus will be on solving tasks such as cataloging books in a library, counting votes in an election, and tracking inventories.

Real-World Application: Cataloging Books in a Library

Suppose you're asked to manage the cataloging of books in a library. Here, the book ID serves as the key, while the details of the book, such as the title, author, and year of publication, are stored as values. This approach allows us to add, search for, and remove books from our library catalog using just a few lines of JavaScript code. // Initializing a Map let libraryCatalog = new Map(); // Details of a book let bookId = "123"; let bookDetails = new Map(); bookDetails.set("title", "To Kill a Mockingbird"); bookDetails.set("author", "Harper Lee"); bookDetails.set("year_published", "1960"); libraryCatalog.set(bookId, bookDetails); // Adding a book to library catalog, where value itself is a Map // Searching for a book if (libraryCatalog.has(bookId)) { let details = libraryCatalog.get(bookId); console.log(`Title: ${details.get("title")}, Author: ${details.get("author")}, Year Published: ${details.get("year_published")}`); } libraryCatalog.delete(bookId); // Removing a book from the library As you can see, Maps make the task of cataloging books in the library simpler and more efficient. You can dynamically add a new book with its unique ID, retrieve its information, and even remove it if necessary.

Real-World Application: Counting Votes in an Election

Imagine a scenario in which we need to count votes in an election. We employ a Map, where each name is a unique key, and the frequency of that name serves as the associated value. Let's write some JavaScript code to better understand this. let votesList = ["Alice", "Bob", "Alice", "Charlie", "Bob", "Alice"]; // Cast votes let voteCounts = new Map(); // Initializing a Map // Counting the votes for (let name of votesList) {voteCounts.set(name, (voteCounts.get(name) || 0) + 1);} for (let [candidate, count] of voteCounts) {console.log(`${candidate}: ${count}`);} // Prints: Alice: 3, Bob: 2, Charlie: 1 Maps facilitate the efficient counting of votes. Using the Map, we can iterate over the votes, increment counts, and ultimately print the results in a straightforward and efficient manner.

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JavaScript

// Initializing a Map
let libraryCatalog = new Map();

// Details of a book
let bookId = "123";
let bookDetails = new Map();
bookDetails.set("title", "To Kill a Mockingbird");
bookDetails.set("author", "Harper Lee");
bookDetails.set("year_published", "1960");

libraryCatalog.set(bookId, bookDetails);  // Adding a book to library catalog, where value itself is a Map

// Searching for a book
if (libraryCatalog.has(bookId)) {
    let details = libraryCatalog.get(bookId);
    console.log(`Title: ${details.get("title")}, Author: ${details.get("author")}, Year Published: ${details.get("year_published")}`);
}

libraryCatalog.delete(bookId);  // Removing a book from the library

// Initializing a Map
let libraryCatalog = new Map();

// Details of a book
let bookId = "123";
let bookDetails = new Map();
bookDetails.set("title", "To Kill a Mockingbird");
bookDetails.set("author", "Harper Lee");
bookDetails.set("year_published", "1960");

libraryCatalog.set(bookId, bookDetails);  // Adding a book to library catalog, where value itself is a Map

// Searching for a book
if (libraryCatalog.has(bookId)) {
    let details = libraryCatalog.get(bookId);
    console.log(`Title: ${details.get("title")}, Author: ${details.get("author")}, Year Published: ${details.get("year_published")}`);
}

libraryCatalog.delete(bookId);  // Removing a book from the library

JavaScript

let votesList = ["Alice", "Bob", "Alice", "Charlie", "Bob", "Alice"];  // Cast votes
let voteCounts = new Map();  // Initializing a Map

// Counting the votes
for (let name of votesList) {
    voteCounts.set(name, (voteCounts.get(name) || 0) + 1);
}

for (let [candidate, count] of voteCounts) {
    console.log(`${candidate}: ${count}`);
}
// Prints: Alice: 3, Bob: 2, Charlie: 1

let votesList = ["Alice", "Bob", "Alice", "Charlie", "Bob", "Alice"];  // Cast votes
let voteCounts = new Map();  // Initializing a Map

// Counting the votes
for (let name of votesList) {
    voteCounts.set(name, (voteCounts.get(name) || 0) + 1);
}

for (let [candidate, count] of voteCounts) {
    console.log(`${candidate}: ${count}`);
}
// Prints: Alice: 3, Bob: 2, Charlie: 1

JavaScript

let storeInventory = new Map();
storeInventory.set("Apples", 100);
storeInventory.set("Bananas", 80);
storeInventory.set("Oranges", 90);  // Initializing an inventory

storeInventory.set("Apples", storeInventory.get("Apples") + 20);  // Updating the number of apples in inventory

let prod = "Apples";  // A product to be checked
console.log(`Total ${prod} in stock: ${storeInventory.get(prod)}`);

// Check if a product is in stock
prod = "Mangoes";
if (storeInventory.has(prod)) {  // If mangoes exist in inventory
    console.log(`${prod} are in stock.`);
} else {  // If mangoes don't exist in inventory
    console.log(`${prod} are out of stock.`);
}

let storeInventory = new Map();
storeInventory.set("Apples", 100);
storeInventory.set("Bananas", 80);
storeInventory.set("Oranges", 90);  // Initializing an inventory

storeInventory.set("Apples", storeInventory.get("Apples") + 20);  // Updating the number of apples in inventory

let prod = "Apples";  // A product to be checked
console.log(`Total ${prod} in stock: ${storeInventory.get(prod)}`);

// Check if a product is in stock
prod = "Mangoes";
if (storeInventory.has(prod)) {  // If mangoes exist in inventory
    console.log(`${prod} are in stock.`);
} else {  // If mangoes don't exist in inventory
    console.log(`${prod} are out of stock.`);
}

JavaScript

// Initializing a Map
let libraryCatalog = new Map();

// Details of a book
let bookId = "123";
let bookDetails = new Map();
bookDetails.set("title", "To Kill a Mockingbird");
bookDetails.set("author", "Harper Lee");
bookDetails.set("year_published", "1960");

libraryCatalog.set(bookId, bookDetails);  // Adding a book to library catalog, where value itself is a Map

// Searching for a book
if (libraryCatalog.has(bookId)) {
    let details = libraryCatalog.get(bookId);
    console.log(`Title: ${details.get("title")}, Author: ${details.get("author")}, Year Published: ${details.get("year_published")}`);
}

libraryCatalog.delete(bookId);  // Removing a book from the library

JavaScript

let votesList = ["Alice", "Bob", "Alice", "Charlie", "Bob", "Alice"];  // Cast votes
let voteCounts = new Map();  // Initializing a Map

// Counting the votes
for (let name of votesList) {
    voteCounts.set(name, (voteCounts.get(name) || 0) + 1);
}

for (let [candidate, count] of voteCounts) {
    console.log(`${candidate}: ${count}`);
}
// Prints: Alice: 3, Bob: 2, Charlie: 1

JavaScript

let storeInventory = new Map();
storeInventory.set("Apples", 100);
storeInventory.set("Bananas", 80);
storeInventory.set("Oranges", 90);  // Initializing an inventory

storeInventory.set("Apples", storeInventory.get("Apples") + 20);  // Updating the number of apples in inventory

let prod = "Apples";  // A product to be checked
console.log(`Total ${prod} in stock: ${storeInventory.get(prod)}`);

// Check if a product is in stock
prod = "Mangoes";
if (storeInventory.has(prod)) {  // If mangoes exist in inventory
    console.log(`${prod} are in stock.`);
} else {  // If mangoes don't exist in inventory
    console.log(`${prod} are out of stock.`);
}

Introduction and Goal Setting

Real-World Application: Cataloging Books in a Library

Real-World Application: Counting Votes in an Election

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Real-World Application: Tracking Store Inventories

Conclusion