I needed a linked list to use in Javascript and couldn't find one so I wrote a simple implementation of it. Not sure if it is the best way, but it works for me :)

Using it:

var ll = new LinkedList(); ll.add(1); ll.add(2); ll.add(3);

for(var n = ll.head; n; n = n.getNext()) console.log('Value: '+ n.getValue() + ' | Previous: ' + (n.getPrevious() == null ? '' : n.getPrevious().getValue()));

ll.insertAfter(3, 4);

for(var n = ll.head; n; n = n.getNext()) console.log('Value: '+ n.getValue() + ' | Previous: ' + (n.getPrevious() == null ? '' : n.getPrevious().getValue()));

ll.replace(1, 100);

for(var n = ll.head; n; n = n.getNext()) console.log('Value: '+ n.getValue() + ' | Previous: ' + (n.getPrevious() == null ? '' : n.getPrevious().getValue()));