Simpliest jQuery ever

jQuery.js

(function(window, document, undefined) {

  function jQuery(selector) {
    this.el = this.slice.call(document.querySelectorAll(selector));
    this.length = this.el.length;

    this.el.forEach(function (element, index) {
      this[index] = element;
    }, this);

    return this;
  }

  jQuery.prototype = {
    each: function (fn) {
      this.el.forEach(function (element, index) {
        fn.apply(element, [element, index]);
      });
      return this;
    },
    slice : [].slice,
    splice : [].splice
  };

  function $(selector) {
    return new jQuery(selector);
  }

  window.$ = $;

}(this, this.document));