Data Structures in JS: Linked Lists

I'm terrible for buying books and courses and never reading or watching them, so I decided to revisit one I bought not so long ago called Learning Data Structures in JavaScript from Scratch. The chap teaching it (Eric Traub) uses repl.it, but I decided to use JSFiddle. Here is the code from the first section, on Linked Lists:

• Constructor Functions and the "this" Keyword https://jsfiddle.net/annoyingmouse/vg12arpf/
• The Prototype Object https://jsfiddle.net/annoyingmouse/1nL6o934/
• Linked List and "Node" Constructor Functions https://jsfiddle.net/annoyingmouse/4bhLtr23/
• Add To Head - part 1 https://jsfiddle.net/annoyingmouse/c6gnft1r/
• Add To Head - part 2 https://jsfiddle.net/annoyingmouse/uthwm1nL/
• Using Add To Head https://jsfiddle.net/annoyingmouse/gd1yo7p0/
• Add To Tail https://jsfiddle.net/annoyingmouse/gpqschf0/
• Testing Add To Tail and Add To Head https://jsfiddle.net/annoyingmouse/8h9gb26q/
• Remove Head https://jsfiddle.net/annoyingmouse/f9upvoyd/
• Remove Tail https://jsfiddle.net/annoyingmouse/hLb7y81w/
• Search Method https://jsfiddle.net/annoyingmouse/pbm6huf5/
• Testing Search https://jsfiddle.net/annoyingmouse/ob1c946w/
• Linked List - Exercise Review https://jsfiddle.net/annoyingmouse/v501emho/
• Big O Notation and Calculating the Runtime of a Function https://jsfiddle.net/annoyingmouse/fbh94cd6/

On the whole, Eric Traub is an engaging tutor, and I learnt a load - well worth a watch. He sometimes speaks a little slowly, but I think that's deliberate, so I watched at 1.25 speed.