gistfile1.js

var query = (function() {
  var query, engine, engines = ('NW.Dom.select,base2.dom.querySelectorAll,Sizzle,$$,$,jQuery,'+
    'YAHOO.util.Selector.query,dojo.query,Ext.DomQuery.select,document.querySelectorAll').split(',');
    
  while (engine = engines.shift()) {
    if (Function('try{ var els = ' + engine + '("*"); return els.length > 0 }catch(e){}')()) {
      query = Function('cssExpr', 'return ' + engine + '(' +
        (/^base2/.test(engine) ? 'document,' : '') + 'cssExpr)');
      break;
    }
  }
  return function(cssExpr) {
    var elements = query(cssExpr), i, result = [ ];
    if (elements && (i = elements.length)) {
      while (i--) {
        result[i] = elements[i];
      }
    }
    return result;
  };
})();