2021-06-04
2977
#vanilla javascript
Paul Ryan
9379
Jun 4, 2021 ⋅ 10 min read

Know your JavaScript data structures

Paul Ryan Developer hailing from Ireland. Loves all things JS and also starting to fall in love with SVGs!

Recent posts:

Kombai AI: The AI agent built for frontend development

Kombai AI converts Figma designs into clean, responsive frontend code. It helps developers build production-ready UIs faster while keeping design accuracy and code quality intact.

Jude Miracle
Oct 23, 2025 ⋅ 7 min read

The Replay (10/22/25): AI-assisted coding, Wasm 3.0, and more

Discover what’s new in The Replay, LogRocket’s newsletter for dev and engineering leaders, in the October 22nd issue.

Matt MacCormack
Oct 22, 2025 ⋅ 29 sec read
Where AI-assisted coding accelerates development — and where it doesn’t

Where AI-assisted coding accelerates development — and where it doesn’t

John Reilly discusses how software development has been changed by the innovations of AI: both the positives and the negatives.

John Reilly
Oct 22, 2025 ⋅ 12 min read
Debugging with Chrome DevTools MCP: Giving AI eyes in the browser

Debugging with Chrome DevTools MCP: Giving AI eyes in the browser

Learn how to effectively debug with Chrome DevTools MCP server, which provides AI agents access to Chrome DevTools directly inside your favorite code editor.

Emmanuel John
Oct 21, 2025 ⋅ 6 min read
View all posts

7 Replies to "Know your JavaScript data structures"

  1. Stack implementation has few errors.
    For example try this code:
    var stack = new Stack();
    stack.push(1);
    stack.peek(); // –> 1
    stack.peek(); // –> undefined, because this._length became -1
    Same problem with pop() method – you decrement this._length three times

  2. `–this.length` is used in error 3 times – decrementing the values instead of retrieving the position. It’s a pretty fundamental error for a data structures tutorial

  3. Hi, in Linked list when I want to remove last node(which is tail), the value of tail stays the same even if it’s deleted. Would this be good way to chage value of the tail? Im still learning.

    if(currentNode === this.tail){
    this.tail = previousNode;
    previousNode.next = currentNode.next;
    return;
    }

  4. There’s a few bugs in the Queue implementation e.g. the `dequeue()` method doesn’t have a `return` statement, so the `firstVal` isn’t returned. If `enqueue(val)` is called multiple times the length can become a negative number, meaning subsequent `peek()` calls return undefined, even after adding values

  5. I updated the article to use an array for the queue, as a note though you wouldn’t use `push` you would use `unshift`

Leave a Reply

Hey there, want to help make our blog better?

Join LogRocket’s Content Advisory Board. You’ll help inform the type of content we create and get access to exclusive meetups, social accreditation, and swag.

Sign up now