Get used selectors from inline stylesheets

gistfile1.js

function getUsedSelectors() {

  var allRules = [];

  _.each(document.styleSheets, function (sheet) {
    var rules;
    if (sheet.rules) {
      rules = _.map(sheet.rules, function (rule) {
        return rule.selectorText;
      });
      allRules.push.apply(allRules, rules);
    }
  });

  return _.filter(allRules, function (rule) {
    return document.querySelector(rule);
  });
}