gistfile1.js

// TODO: should probably convert result to plain array (since different engines return different things -- arrays, nodelists, objects, etc.)
var query = (function() {
  var engine, engines = 'NW.Dom.select,base2.dom.querySelectorAll,Sizzle,$$,$,YAHOO.util.Selector.query,dojo.query,Ext.DomQuery.select'.split(',');
  while ((engine = engines.shift())) {
    if (Function('try{return ' + engine + '}catch(e){}')()) {
      return Function('cssExpr, ctx', 'ctx || (ctx = document);return ' + engine + '(' +
        (engine.indexOf('base2') > -1 ? 'ctx, cssExpr' : 'cssExpr, ctx') + ')');
    }
  }
  return 'querySelectorAll' in document ?
    function(cssExpr, ctx) {
      ctx || (ctx = document);
      return ctx.querySelectorAll(cssExpr);
  } : Function('return []');
})();