Lookahead regex

Had a situation where I wanted to split a guitar tuning string into an array of individual notes.

var algernon = "DAEAC#E";

var algernonNotes = algernon.split(/([A-G][#b]?)/); // [ '', 'D', '', 'A', '', 'E', '', 'A', '', 'C#', '', 'E', '' ]

Well, cb diam la. I don’t want the empty strings. I found two ways of addressing this conundrum:

var algernon = "DAEAC#E";

var algernonNotes = algernon.split(/(?=[A-G][#b]?)/); // [ 'D', 'A', 'E', 'A', 'C#', 'E' ]
var algernonNotes = algernon.split(/([A-G][#b]?)/).filter(Boolean); // [ 'D', 'A', 'E', 'A', 'C#', 'E' ]

So the first approach uses a Lookahead regex, while the second approach calls filter() to remove the empty strings since they evaluate to false. Gonna have to look into this lookahead stuff. And the Ruby equivalent:

var algernon = "DAEAC#E";

var algernonNotes = algernon.split(/(?=[A-G][#b]?)/); // [ 'D', 'A', 'E', 'A', 'C#', 'E' ]
var algernonNotes = algernon.split(/([A-G][#b]?)/).reject(&:empty?); // [ 'D', 'A', 'E', 'A', 'C#', 'E' ]