Get all class names of a document. Useful for... whatever.

Get all class names.js

var classes = [];
Array.prototype.forEach.call(document.querySelectorAll('*'), function(el) {
  el.className.split(/\s/).forEach(function(cl) {
    if (cl && classes.indexOf(cl) == -1)
	  classes.push(cl);
  });
});
classes.sort();
classes.forEach(function(cl) {
  console.log(cl);
});