Great question! 👏 It takes many traits to reach the "extraordinary" level, as a developer, and the answers before me have done a great job at listing a few of them. Adding to them, or rather extending from them, here's a list that stood out for me, from my experience so far.

I had to jump on the JavaScript bandwagon towards the end of 2015, when I quit my stint in Computational Biology (which involved a lot of Python, and a bit of C), and joined a web shop whose arsenal primarily included NodeJS.
Prior to my joining, they migrated their front-end setup from BackboneJS to ReactJS. At that point in time I didn't even have the faintest idea as to what React was, and what it entailed. Sanjay, the former CTO, (now pursuing research at MIT Media Lab) had this assignment for me.
Build a VanillaJS implementation of a Todo App, whose data layer is completely decoupled from the UI, and any change in the UI should update the data. A UI render should only happen, and only depend (both during initialisation, and while handling changes) on the data layer. Basically, the UI should be a pure function of the data.
I thought, that was a pretty rad design pattern ... and I came up with an implementation, soon after that. It was only after a bit later — when I was introduced to React, and the core principles behind it — when I realised the whole gist of React:
var UI = function(data)
Sanjay started the process of teaching React without actually teaching React, and when I realised it, it ended up being one of my best aha moments.

In science, computing, and engineering, a black box is a device, system or object which can be viewed in terms of its inputs and outputs (or transfer characteristics), without any knowledge of its internal workings. Its implementation is "opaque" (black). Almost anything might be referred to as a black box: a transistor, an algorithm, or the human brain.
Extending on what @spsiddarthan said in his third point, the solutions cooked up by these bunch of "extraordinary" developers; gracefully handle all of the corner cases. They go up a notch, by taking it upon them to design code in a beautifully modularised way; which makes the process of "plug and play", with the "whole" parts of their code incredibly easy.
Not only that, they strive to help you write code in the same way.

If writing great code is on one hand; to have an innate knowledge of the entire system, and how additional "moving" parts, so to speak, would be, and should be introduced (read: modular black boxes), and how they would work with other parts of the system is a total different ball game; and they excel at it.