模仿jq写个库 完善中 。。。

(function() {
  var es = function(selector) {
    return new es.prototype.init(selector);
  };

  es.domReady = function(fn) {
    document.addEventListener("DOMContentLoaded", function() {
      fn && fn();
    }, false);

  };

  es.each = function(obj, cb) {
    var ret, i = 0;
    if (obj.length === +obj.length) { //鸭辩
      while(obj.length !== i) {
        ret = cb.call(obj[i], i, obj[i]);
        if (ret === "break") {
          break;
        }
        if (ret !== undefined) {
          return ret;
        }
        i++;
      }
    }

    else if (obj instanceof Object) {
      for (var k in obj) {
        if (obj.hasOwnProperty(k)) {
          ret = cb.call(obj[k], k, obj[k]);
          if (ret === "break") {
            break;
          }
          if (ret !== undefined) {
            return ret;
          }
        }
      }
    }
  };

  es.event = function() {
    var events = [];
    var types = ["click"]
    return {
      on: function(type, cb) {
        var arr = events[type] = events[type] || [];

        if (types.indexOf(type) !== -1) {
          es.each(this, function(i, el) {
            el.addEventListener(type, cb);
          });
        }

        if (arr.indexOf(cb) === -1) {
          arr.push(cb);
        }
        return this;
      },
      off: function(type, cb) {
        var arr = events[type] = events[type] || [], i = 0;

        //传统事件
        if (types.indexOf(type) !== -1) { 
          es.each(this, function(i, el) {
            cb && el.removeEventListener(type, cb);
            if (!cb) {
              es.each(events[type], function(i, cb) {
                el.removeEventListener(type, cb);
              });
            }
          });
        }

        if(!cb) events[type] = [];
        cb && es.each(arr, function(i, fn) {
          if (fn === cb) {
            arr.splice(i, 1);
            return "break";
          }  
        });

        return this;
      },
      emit: function(type) {
        var arr = events[type] = events[type] || [], self = this, argv = arguments;
        es.each(arr, function(i, fn) {
          fn.apply(self, [].slice.call(argv, 1));
        });
      }
    }
  }();

  es.ajax = function (opt) {
    var callback = opt.callback || function() {};
    var type = opt.type || "GET";
    var req = new XMLHttpRequest();
    req.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    req.open(type, URL, true);
    req.onreadystatechange = function() {
      if (req.status === 200) {
        callback(null, req.responseText);
      } else {
        callback(new Error(req.statusText), req.response);
      }
    };
    req.onerror = function() {
      callback(new Error(req.statusText));
    };
    req.send(opt.data ? opt.data : null);
  };

  es.get = function(url, data, callback) {
    es.ajax({
      url : url,
      data: data,
      callback : callback
    });
  };

  es.post = function(url, callback) {
    es.ajax({
      type: "POST",
      data: data,
      callback: callback
    });
  };

  var oo = es.prototype = {
    constructor: es,
    splice: [].splice,
    shift: [].shift,
    push: [].push,
    length: 0,
  };
  

  oo.init = function(selector) {
    var els;

    if (typeof selector === "string") {
      els = document.querySelectorAll(selector), els = [].slice.call(els, 0);
    } else if(selector instanceof HTMLElement) {
      els = [selector];
    } else if (selector instanceof es) {
      return es;
    } else if (selector instanceof Array) {
      els = selector;
    }

    while(els[0]) {
      this.push(els.shift());
    }
  };

  oo.init.prototype = oo;

  oo.each = function(cb) {    
    return es.each(this, function(i, el) {
      return cb.call(el, i, el);
    });
  };

  oo.is = function(name) {
    return es.each(this, function(i, el) {
      if (name.slice(0, 1) === "#") {
        return el.id === name.slice(1);
      }
      else if(name.slice(0, 1) === ".") {
        return el.classList.contains(name.slice(1));
      }
      else {
        return el.tagName.toLowerCase() === name.toLowerCase()
      }
    });
  };

  oo.addClass = function(cls) {
    es.each(this, function(i, el) {
      el.classList.add(cls);
    });
    return this;
  };

  oo.removeClass = function(cls) {
    es.each(this, function(i, el) {
      el.classList.remove(cls);
    });
    return this;
  };

  oo.addStyle = function(cssText) {
    es.each(this, function(i, el) {
      el.style.cssText = cssText;
    });
    return this;
  };

  oo.next = function() {
    var self = this;
    es.each(this, function(i, el) {
      self[i] = el.nextElementSibling;
    });
    return this;
  };


  oo.prev = function() {
    var self = this;
    es.each(this, function(i, el) {
      self[i] = el.previousElementSibling;
    });
    return this;
  };

  oo.parent = function(selector) {
    var parent = [];
    es.each(this, function(i, el) {
      if (parent.indexOf(el.parentNode) === -1) {
        parent.push(el.parentNode);
      }
    });

    this.length = 0;
    while(parent[0]) {
      var el = parent.shift();
      if (selector) {
        es(el).is(selector) && this.push(el);
      } else {
        this.push(el);
      }
    };
    return this;
  };

  oo.children = function(selector) {
    var children = [], el;
    es.each(this, function(i, el) {
      children = children.concat([].slice.call(el.children, 0));
    });

    this.length = 0;

    while(children[0]) {
      el = children.shift();
      if (!selector) {
        this.push(el);
      }
      if (selector && es(el).is(selector)) {
        this.push(el);
      } 
    }
    return this;
  };

  oo.find = function(selector) {
    var all = [];
    es.each(this, function(i, el) {
      all = all.concat([].slice.call(el.querySelectorAll(selector), 0));
    });

    this.length = 0;
    while(all[0]) {
      this.push(all.shift());
    }
    return this;
  };

  oo.first = function() {
    return es(this[0]);
  };

  oo.last = function() {
    return es(this[this.length - 1]);
  };

  oo.attr = function(key, value) {
    if (value === undefined) {
      return es.each(this, function(i, el) {
        return el.getAttribute(key);
      });
    }

    es.each(this, function(i, el) {
      el.setAttribute(key, value);
    });
    return this;
  };

  es.insert = function (arr, pos, str) {
    es.each(arr, function(i, el) {
      el.insertAdjacentHTML(pos, str);
    });
  };

  oo.append = function(str) {
    if (typeof str === "string") {
      es.insert(this, "beforeend", str);
    } 

    if (str instanceof HTMLElement) {
      es.each(this, function(i, el) {
        el.appendChild(str);
        return "break";
      });
    }
    return this;
  };

  oo.after = function(str) {
    es.insert(this, "afterend", str);
    return this;
  };

  oo.before = function(str) {
    es.insert(this, "beforebegin", str);
    return this;
  };

  oo.prepend = function(str) {
    es.insert(this, "afterbegin", str);
    return this;
  };

  oo.on = es.event.on;
  oo.off = es.event.off;
  oo.emit = es.event.emit;

  window.es = es;

})();