Benchmark: Array vs Linked List

Script Preparation code:

/**
 * Linked List base code courtesy Nicholas C Zakas. Additional methods are my own.
 */
function LinkedList() {
  /**
   * Pointer to first item in the list.
   * @property _head
   * @type Object
   * @private
   */
  this._head = null;
}

function createNode(data, next) {
  return {
    data: data,
    next
  };
}

LinkedList.prototype = {
  //restore constructor
  constructor: LinkedList,

  /**
   * Appends some data to the end of the list. This method traverses
   * the existing list and places the value at the end in a new item.
   * @param {variant} data The data to add to the list.
   * @return {Void}
   * @method add
   */
  push: function(data) {
    //create a new item object, place data in
    var node = createNode(data);

    //used to traverse the structure
    var current;

    //special case: no items in the list yet
    if (this._head === null) {
      this._head = node;
    } else {
      current = this._head;

      while (current.next) {
        current = current.next;
      }

      current.next = node;
    }
  },

  /**
   * Like its array counterpart, unshift appends an item to the beginning of the list
   */
  unshift: function(data) {
    var node = createNode(data);

    //special case: no items in the list yet
    if (this._head === null) {
      this._head = node;
    } else {
      node.next = this._head;
      this._head = node;
    }
  },

  /**
   * Like its array counterpart, shift removes and returns the first item of the list
   */
  shift: function() {
    const node = this._head;
    this._head = this._head.next;
    return node;
  },

  /**
   * Retrieves the data in the given position in the list.
   * @param {int} index The zero-based index of the item whose value
   *      should be returned.
   * @return {variant} The value in the "data" portion of the given item
   *      or null if the item doesn't exist.
   * @method item
   */
  item: function(index) {
    //check for out-of-bounds values
    if (index > -1) {
      var current = this._head,
        i = 0;

      while (i++ < index && current) {
        current = current.next;
      }

      return current ? current.data : null;
    } else {
      return null;
    }
  },

  /**
   * Removes the item from the given location in the list.
   * @param {int} index The zero-based index of the item to remove.
   * @return {variant} The data in the given position in the list or null if
   *      the item doesn't exist.
   * @method remove
   */
  remove: function(index) {
    //check for out-of-bounds values
    if (index > -1) {
      var current = this._head,
        previous,
        i = 0;

      //special case: removing first item
      if (index === 0) {
        this._head = current.next;
      } else {
        //find the right location
        while (i++ < index) {
          previous = current;
          current = current.next;
        }

        //skip over the item to remove
        previous.next = current.next;
      }

      //return the value
      return current ? current.data : null;
    } else {
      return null;
    }
  }
};

Tests:

Linked List
var list = new LinkedList(); var x = 10000; while(x--) { list.unshift(x); }
Array
var array = []; var x = 10000; while(x--) { array.unshift(x); }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Linked List
Array

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one month ago)

User agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/146.0.0.0 Safari/537.36

Browser/OS: Chrome 146 on Linux

View result in a separate tab

Test name	Executions per second
Linked List	30783.4 Ops/sec
Array	480.6 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the benchmark and explain what's being tested, compared, and their pros and cons.

**What is being tested?**

The benchmark compares the performance of two data structures: Arrays and Linked Lists. The specific test cases are:

1. "Linked List" (test case): Appending 10,000 elements to the beginning of a linked list using `unshift()`.
2. "Array" (test case): Appending 10,000 elements to the beginning of an array using `unshift()`.

**Comparison**

The comparison is between two approaches:

1. **Linked List**: A custom implementation of a singly-linked list with `push`, `unshift`, `shift`, and `item` methods.
2. **Array**: The built-in JavaScript Array object with the `unshift` method.

**Pros and Cons:**

**Linked List:**

Pros:

* Can be more efficient for large datasets since it only needs to traverse the list until the insertion point, rather than shifting all elements after each insertion.
* Allows for O(1) insertion at the beginning of the list (using `unshift`).

Cons:

* Requires manual memory management (e.g., keeping track of node references).
* Can be slower in practice due to the overhead of traversing the list.

**Array:**

Pros:

* Built-in and optimized by JavaScript engine for performance.
* Easy to use and integrate into existing code.

Cons:

* Can be less efficient for large datasets since it requires shifting all elements after each insertion, resulting in O(n) time complexity.
* Limited control over the underlying implementation.

**Other Considerations:**

The benchmark uses Firefox 131 as the testing browser, which may not represent the entire user base. Additionally, the test cases only involve appending elements to the beginning of the data structure, which might not be a realistic use case for most applications.

**Alternatives:**

If you need to implement a linked list or array in JavaScript, consider the following alternatives:

* **Native Linked List**: You can create a custom implementation using JavaScript objects and arrays. This approach provides control over the underlying implementation but requires manual memory management.
* **JavaScript libraries**: Libraries like jQuery, Lodash, or even vanilla Node.js modules (e.g., `node-queue`) provide built-in linked list implementations that simplify development and manage memory automatically.
* **Native Array**: If you're working with a modern JavaScript engine, using the built-in array implementation is usually the best choice for most use cases.

Related benchmarks:

Array vs Linked List (version: 2)

Manage Todos in a list - compare performance of Array vs Linked List.

Comparing performance of: Linked List vs Array

Created: 8 years ago by: Registered User

Jump to the latest result

Linked List

Array

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):