List all selectors across DOM stylesheets

list-selectors-across-stylesheets.js

function logSortedCSSSelectorsOnStylesheets(stylesheets) {
  var ruleset = new Set();
  for (var stylesheet in stylesheets) {
    var rules = stylesheets[stylesheet].rules;
    for (var rule in rules) {
      var stylesheetRule = rules[rule];
      if (stylesheetRule.selectorText) {
        ruleset.add(stylesheetRule.selectorText);
      }
    }
  }

  ruleset = Array.from(ruleset).sort();

  for (var rule in ruleset) {
    console.log(ruleset[rule]);
  }  
}
var stylesheets = document.styleSheets;
logSortedCSSSelectorsOnStylesheets(stylesheets);