Understand ⏱ 120 min

Data Structures and Algorithms in JavaScript – Full Course for Beginners

What You Will Learn

Understand the concept of a stack data structure and its Last-In-First-Out (LIFO) behavior
Learn how to implement a stack using an array in JavaScript
Discover how to use a stack to solve problems, such as checking for palindromes

Key Concepts

A stack is a data structure that follows the Last-In-First-Out (LIFO) principle, meaning the last item added to the stack is the first one to be removed. This can be visualized using a physical stack of books, where the topmost book is the one that was added last and will be the first one to be taken off. The stack has several key methods, including push (adding an item to the top of the stack), pop (removing the top item from the stack), and peek (viewing the top item without removing it). In JavaScript, an array can be used as a stack because it has built-in methods that support these operations. The concept of a palindrome, a word that reads the same forwards and backwards, can be used to demonstrate the practical application of a stack.

Code Examples

if (word === rword) // checks if a word is a palindrome

This code snippet checks if a word is the same when reversed, indicating that it is a palindrome.

for (let i = 0; i < word.length; i++) { // pushes each letter of a word onto a stack
    letters.push(word[i]);
}

This code pushes each letter of a word onto a stack, allowing the word to be reversed and checked for palindromes.

return this.storage[this.count - 1]; // returns the top item on the stack without removing it

This code returns the top item on the stack without removing it, demonstrating the peek method.

Lesson Summary

In this lesson, we explored the concept of a stack data structure and its application in JavaScript. We learned that a stack follows the Last-In-First-Out (LIFO) principle, where the last item added is the first one to be removed. We saw how an array can be used as a stack in JavaScript, using methods like push, pop, and peek. The instructor demonstrated how to use a stack to check for palindromes, a word that reads the same forwards and backwards. By reversing a word using a stack, we can compare the original word with its reverse to determine if it is a palindrome. This lesson provided a solid introduction to stacks and their practical application in programming.

Practice Exercise

Create a function that uses a stack to check if a sentence is a palindrome, ignoring spaces and punctuation. For example, “A man, a plan, a canal: Panama” should return true.

What Is Next

In the next lesson, we will explore another fundamental data structure, the queue, and learn how to implement it in JavaScript. We will discover how queues differ from stacks and how they can be used to solve real-world problems.

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