my-jquery.js

(function() {
  $ = function(selector) {
      // tesla instanceof Tesla
      if(!(this instanceof $)) {
          return new $(selector);
      }
      var elements;
      if(typeof selector === "string") {
           elements = document.querySelectorAll(selector);
      } else {
          elements = selector;
      }

      for(var i  = 0; i< elements.length; i++) {
          this[i] = elements[i];
      }

      this.length = elements.length;
  };

  // target = {}
  // o1 = {foo:"bar", zed: "ted"}
  // o2 = {}
  // extend(target, [o1, o2])
  // target //-> {0: o1, 1: o2, length: 2}
  $.extend = function(target, source) {
      for( var prop in source ) {
          target[prop] = source[prop];
      }
      return target;
  };

  // Static methods

  var isArrayLike = function(obj) {
      if(obj && typeof obj.length === "number") {
          if(obj.length >  0) {
              return (obj.length - 1) in obj;
          } else {
              return obj.length === 0;
          }
      } else {
          return false;
      }
  };

  // $.each([1,2,3], function(index, value, collection){  this //-> collection })

  $.extend($, {
    isArray: function(obj) {
        return Object.prototype.toString.call(obj) === "[object Array]";
    },
    each: function(collection, cb) {
        if(isArrayLike(collection)) {
            for(var i  = 0 ; i < collection.length; i++) {
                if( cb.call(collection, i, collection[i], collection) === false ) {
                    break;
                }
            }
        } else {
            for(var prop in collection) {
                if( cb.call(collection, prop, collection[prop], collection) === false ) {
                    break;
                }
            }
        }
        return collection;
    },
    makeArray: function(arr) {
        var array = [];
        $.each(arr, function(index, value){
            array.push(value);
        })
        return array;
    },
    proxy: function(fn, context) {
        return function(){
            return fn.apply(context, arguments);
        };
    }
  });


  function getText(el) {
      var text = "";
      $.each(el.childNodes, function(i, node){
          if(node.nodeType === Node.ELEMENT_NODE) {
              text += getText(node);
          }else if(node.nodeType === Node.TEXT_NODE) {
              text += node.nodeValue; // add to accumulator
          }
      });
      return text;
  }

  function makeMutator(property) {
      return function(newHtml) {
          if(arguments.length) {
              return $.each(this, function(i, element){
                  element[property] = newHtml;
              });
          } else {
              return this[0][property];
          }
      }
  }
  function makeTraverser(traverse) {
      return function(){
          var newElements = [];
          var args = arguments;
          $.each(this, function(i, element){
              var elements = traverse.apply(element, args);
              if(elements) {
                  if(isArrayLike(elements)) {
                      Array.prototype.push.apply(newElements, elements);
                  } else {
                      newElements.push(elements);
                  }
              }
          });
          return $(newElements) //-> instanceof jQuery
      };
  }

  function makeGetSibling(property){
      return function(){
          var next = this[property];
          while(next && next.nodeType !== Node.ELEMENT_NODE) {
              next = next[property];
          }
          return next;
      }
  }

  $.extend($.prototype, {
    html: makeMutator("innerHTML"),
    val: makeMutator("value"),
    text: function(newText) {
        if(arguments.length) {
            this.html("");
            return $.each(this, function(i, element){
                element.appendChild( document.createTextNode(newText) )
            });
        } else {
            return getText(this[0]);
        }
    },
    // $('div').find('img') //-> $images
    find: makeTraverser(function(selector){
        return this.querySelectorAll(selector);
    }),
    next: makeTraverser(makeGetSibling("nextSibling")),
    prev: makeTraverser(makeGetSibling("previousSibling")),
    parent: makeTraverser(function(){
        return this.parentNode;
    }),
    children: makeTraverser(function(){
        return this.children;
    }),
    attr: function(attrName, value) {},
    css: function(cssPropName, value) {},
    width: function() {},
    offset: function() {
      var offset = this[0].getBoundingClientRect();
      return {
        top: offset.top + window.pageYOffset,
        left: offset.left + window.pageXOffset
      };
    },
    hide: function() {},
    show: function() {},

    // Events
    bind: function(eventName, handler) {},
    unbind: function(eventName, handler) {},
    has: function(selector) {
      var elements = [];

      $.each(this, function(i, el) {
        if(el.matches(selector)) {
          elements.push(el);
        }
      });

      return $( elements );
    },
    on: function(eventType, selector, handler) {
      return this.bind(eventType, function(ev){
        var cur = ev.target;
        do {
          if ($([ cur ]).has(selector).length) {
            handler.call(cur, ev);
          }
          cur = cur.parentNode;
        } while (cur && cur !== ev.currentTarget);
      });
    },
    off: function(eventType, selector, handler) {},
    data: function(propName, data) {},

    // Extra
    addClass: function(className) {},
    removeClass: function(className) {},
    append: function(element) {}
  });

  $.buildFragment = function(html) {};
})();