2021-06-04
2977
#vanilla javascript
Paul Ryan
9379
Jun 4, 2021 â‹… 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:

i tried kiro and here is what i learned

I tried out Kiro: Here’s what I learned

Check out Kiro, AWS’s AI-powered IDE, see what makes it different from other AI coding tools, and explore whether it lives up to the hype.

Elijah Asaolu
Aug 28, 2025 â‹… 5 min read
Go Design Pattern Article Image With Logo

Why Go design patterns still matter

Here’s how three design patterns solved our Go microservices scaling problems without sacrificing simplicity.

Peter Aideloje
Aug 28, 2025 â‹… 2 min read
how to protect your ai agent from prompt injection attacks

How to protect your AI agent from prompt injection attacks

Explore six principled design patterns (with real-world examples) to help you protect your LLM agents from prompt injection attacks.

Rosario De Chiara
Aug 27, 2025 â‹… 5 min read
Don’t Let AI Erase The Next Generation Of Dev Leaders

Don’t let AI erase the next generation of dev leaders

As AI tools take over more routine coding work, some companies are cutting early-career dev roles — a short-sighted move that could quietly erode the next generation of tech leaders if we aren’t careful.

Jack Herrington
Aug 26, 2025 â‹… 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