Find all the pseudos

pseudos.js

(function() {
    var selectors = new Map();
    for (let sheet of Array.from(document.styleSheets)) {
        for (let rule of Array.from(sheet.cssRules || [])) {
            var text = rule.selectorText || "";
            for (let match of (text.match(/\:([a-zA-Z0-9\-]+)/g) || []))
                selectors.set(match, (selectors.get(match) || 0) + 1);
        }
    }
    return [
        selectors,
        // We need to allocate each one at least once, so subtract the set size.
        Array.from(selectors.values()).reduce((total, value) => total + value, 0) - selectors.size,
    ];
})();