IE7 polyfill for document.querySelectorAll

qsa-polyfill-ie7.js

if (!document.querySelectorAll) {
  document.querySelector = function(selector) {
    return document.querySelectorAll(selector)[0];
  }

  document.querySelectorAll = function(selector) {
    if (document.__querySelectorAllStylesheet === undefined) {
      document.__querySelectorAllStylesheet = document.createStyleSheet();
    }

    var stylesheet = document.__querySelectorAllStylesheet;

    var all = document.all;
    var results = [ ];

    selector = selector.replace(/\[for\b/gi, '[htmlFor').split(',');

    for (var i = selector.length; i--;) {
      stylesheet.addRule(selector[i], 'k:v');

      for (var j = all.length; j--;) {
        (all[j].currentStyle.k && results.push(all[j]));
      }

      stylesheet.removeRule(0);
    }

    return results;
  }
}