Data Structure: Linked List in JavaScript

Overview

A Linked list is a linear data structure that includes a series of connected nodes. Each node contains a value and a reference (or pointer) to the next node in the sequence.

The list elements can be easily inserted or removed without reallocation or reorganization of the entire structure.

Random access of elements is not feasible and accessing an element has linear time complexity.

The linked list data structure supports three main operations

• Insertion - to add an element at the beginning, end or at a given index in the list
• Deletion - to remove an item given its index or value
• Search - to find an element given its value

Linked List Usage

• All applications of both stacks and queues are applications of linked list.
• Image Viewer
• Music Player
• Video Player

class Node {
    constructor(value) {
        this.value = value
        this.next = null
    }
}

class LinkedList {
    constructor() {
        this.head = null
        this.size = 0
    }

    isEmpty() {
        return this.size === 0
    }

    getSize() {
        return this.size
    }

    prepend(value) {
        const node = new Node(value);
        if (this.isEmpty()) {
            this.head = node
        }
    }
}

const list = new LinkedList()
console.log(list.isEmpty()) // true
console.log(list.getSize()) // 0

Why this still matters when AI writes your code

In everyday JavaScript, a plain array is usually faster than a linked list because of memory locality, so reach for a linked list only when you genuinely need cheap insertion or removal at a node you already hold.

Where it matters is in understanding: pointers and references are the foundation of trees, graphs, LRU caches and many interview and system-design problems. And it is a place where generated code goes wrong in predictable ways:

• Losing the reference to the head while relinking nodes.
• Off-by-one errors when inserting or deleting at an index.
• Accidentally creating a cycle, which turns a traversal into an infinite loop.

Draw the pointers on paper when you review one; it catches most of these.

This is part of the Data Structures in JavaScript series. For the bigger picture, read Fundamentals Over Frameworks.