Pen Settings

HTML

CSS

CSS Base

Vendor Prefixing

Add External Stylesheets/Pens

Any URL's added here will be added as <link>s in order, and before the CSS in the editor. If you link to another Pen, it will include the CSS from that Pen. If the preprocessor matches, it will attempt to combine them before processing.

+ add another resource

JavaScript

Babel includes JSX processing.

Add External Scripts/Pens

Any URL's added here will be added as <script>s in order, and run before the JavaScript in the editor. You can use the URL of any other Pen and it will include the JavaScript from that Pen.

+ add another resource

Packages

Add Packages

Search for and use JavaScript packages from npm here. By selecting a package, an import statement will be added to the top of the JavaScript editor for this package.

Behavior

Save Automatically?

If active, Pens will autosave every 30 seconds after being saved once.

Auto-Updating Preview

If enabled, the preview panel updates automatically as you code. If disabled, use the "Run" button to update.

Format on Save

If enabled, your code will be formatted when you actively save your Pen. Note: your code becomes un-folded during formatting.

Editor Settings

Code Indentation

Want to change your Syntax Highlighting theme, Fonts and more?

Visit your global Editor Settings.

HTML

              
                
              
            
!

CSS

              
                
              
            
!

JS

              
                function Node(value) {
  return {
    value,
    next: null
  }
}

class LinkedList {
  constructor() {
    this.head = null;
    this.tail = null;
    this.length = 0;
  }
  
  push(value) {
    const node = Node(value);
    // The list is empty
    if (this.head === null) {
      this.head = node;
      this.tail = node;
      this.length++;
      return node;
    }
    this.tail.next = node;
    this.tail = node;
    this.length++;
  }
    
  pop() {
    if (this.isEmpty()) {
      return null;
    }
    
    const nodeToRemove = this.tail;

    // There's only one node!
    if (this.head === this.tail) {
      this.head = null;
      this.tail = null;
      this.length--;
      return nodeToRemove;
    }
    
    let currentNode = this.head;
    let secondToLastNode;
    
    // Start at the front and iterate until
    // we find the second to last node
    while (currentNode) {
      if (currentNode.next === this.tail) {
        // Move the pointer for the second to last node
        secondToLastNode = currentNode;
        break;
      }
      currentNode = currentNode.next;
    }
    // Pop off that node
    secondToLastNode.next = null;
    // Move the tail to the second to last node
    this.tail = secondToLastNode;
    this.length--;
    
    // Initialized to this.tail
    return nodeToRemove;
  }
    
  get(index) {
    // Index is outside the bounds of the list
    if (index < 0 || index > this.length) {
      return null;
    }
    
    if (this.isEmpty()) {
      return null;
    }
    
    // We're at the head!
    if (index === 0 )  {
      return this.head;
    }
    
    let current = this.head;
    let iterator =  0;
    
    while (iterator < index) {
      iterator++;
      current = current.next;
    }
    
    return current;
  }
    
  delete(index) {
     // Index is outside the bounds of the list
    if (index < 0 || index > this.length - 1) {
      return null;
    }
    
    if (this.isEmpty()) {
      return null;
    }
    
    if (index === 0) {
      const nodeToDelete = this.head;
      this.head = this.head.next;
      this.length--;
      return nodeToDelete;
    }
    
    let current = this.head;
    let previous;
    let iterator = 0;
    
    while (iterator < index) {
      iterator++;
      previous = current;
      current = current.next;
    }
    const nodeToDelete = current;
    // Re-direct pointer to skip the element we're deleting
    previous.next = current.next;
    
    // We're at the end
    if(previous.next === null) {
      this.tail = previous;
    }
    
    this.length--;
    
    return nodeToDelete;
  }
    
  isEmpty() {
    return this.length === 0;
  }
  
  printList () {
    const nodes = [];
    let current = this.head;
    while (current) {
      nodes.push(current.value);
      current = current.next;
    }
    return nodes.join(' -> ');
  }
}

const myList = new LinkedList();
const values = ['a', 'b', 'c', 'd', 'e'];
values.forEach(value => myList.push(value));
console.log(myList.printList()); // 'a -> b -> c -> d -> e'
myList.pop();
myList.pop();
console.log(myList.printList()); // 'a -> b -> c
myList.push('x');
myList.push('y');
myList.push('z');
console.log(myList.printList()); // 'a -> b -> c -> x -> y -> z
myList.delete(3);
console.log(myList.printList()); // 'a -> b -> c -> y -> z
console.log(myList.get(3));

              
            
!
999px

Console