Minimal css selector

query.js

/**
 * Minimal CSS selector engine for modern browsers.
 * @param {String} selector A string containing a selector expression.
 * @param {Node=} opt_context The context to search within.
 * @returns {Node|NodeList} An element or list of matched elements.
 */

window.$$ = function(selector, opt_context) {
  var context = opt_context || document;
  var results = context.querySelectorAll(selector);
  return results.length > 1 ? results : results[0];
}