In your documentation you state that this plugin uses alphanumeric, but it seems to use natural sort order. That is that x7, x8 and x70, is sorted according to the number sequence of 7, 8, 70, and not ...

var compare = require('alphanumeric-sort').compare; ["file 100.txt", "file 5.txt", "file 39.txt"].sort(compare); //=> ["file 5.txt", "file 39.txt", "file 100.txt ...