mini jquery

function $(id){
        var el = 'string' == typeof id
          ? document.getElementById(id)
          : id;

        el.on = function(event, fn){
          if ('content loaded' == event) {
            event = window.attachEvent ? "load" : "DOMContentLoaded";
          }
          el.addEventListener
            ? el.addEventListener(event, fn, false)
            : el.attachEvent("on" + event, fn);
        };

        el.all = function(selector){
          return $(el.querySelectorAll(selector));
        };

        el.each = function(fn){
          for (var i = 0, len = el.length; i < len; ++i) {
            fn($(el[i]), i);
          }
        };

        el.getClasses = function(){
          return this.getAttribute('class').split(/\s+/);
        };

        el.addClass = function(name){
          var classes = this.getAttribute('class');
          el.setAttribute('class', classes
            ? classes + ' ' + name
            : name);
        };

        el.removeClass = function(name){
          var classes = this.getClasses().filter(function(curr){
            return curr != name;
          });
          this.setAttribute('class', classes.join(' '));
        };

        return el;
      }