jQuery-like-lib.js

var jQuery = (function jQueryClass(win, doc) {

  var AP = Array.prototype;
  
  function jQuery(selector) {
    this.el = this._init(selector);
    this.length = this.el.length;
  }
  
  function $(selector) {
    return new jQuery(selector);    
  }
  
  jQuery.prototype = {
    _init: function(selector) {
      return AP.slice.call(doc.querySelectorAll(selector));
    }
  };
  
  return win.$ = $;
  
}(window, document));