itcast.extend({
    nextSibling: function(dom) {
        var nextNode = dom;
        while(nextNode = nextNode.nextSibling) {
            if(nextNode.nodeType === 1) {
                return nextNode;
            }
        }
    }
});

itcast.fn.extend({
    next: function() {
        var arr = [];
        itcast.each(this, function() {
            arr.push( itcast.nextSibling(this) );
        });
        return itcast(arr);
    }
});

itcast.extend({
    nextAll: function(dom) {
        var newDom, arr = [];
        while(newDOM = dom.nextSibling) {
            if(newDom.nodeType === 1) {
                arr.push(newDom);
            }
        }
        return arr;
    }
});

itcast.fn.extend({
    nextAll: function() {
        var arr = [];
        itcast.each(this, function(i, v) {
            itcast.push.apply(arr, itcast.nextAll(v));
        });

        return itcast(arr);
    }
});

itcast.extend({
    select: select
});

// 使用 Sizzle 替换 select
itcast.select = Sizzle;

onclick / onmouseenter / onmouseleave / onmouseover / onmouseout
onkeydown / onkeyup / onfocus / onblur
on...

dv.onclick = function() {

};

<button onclick="alert(‘划船不用桨‘);"></button>
<button onclick="fn();"></button>

<script>
    function fn() {
        alert("划船不用桨");
    }
</script>

// 参数一：事件名
// 参数二：事件处理程序
// 参数三：false表示冒泡，true表示捕获
dv.addEventListener("click", function() {}, false);

// 参数一：事件名
// 参数二：事件处理程序
dv.attachEvent("onclick", function() {});

itcast.fn.extend({
    click: function(callback) {
        this.each(function() {
            this.onclick = callback;
        });
    }
});

itcast.fn.extend({
    click: function(callback) {
        this.each(function() {
            this.addEventListener("click", callback);
        });
        return this;
    }
});

itcast.fn.extend({
    on: function(type, callback) {
        this.each(function() {
            if(this.addEventListener) {
                this.addEventListener(type, callback);
            } else {
                this.attachEvent("on" + type, callback);
            }
        });

        return this;
    },
    off: function() {
        this.each(function() {
            if(this.removeEventListener) {
                this.removeEventListener(type, callback);
            } else {
                this.detachEvent("on" + type, callback);
            }
        });

        return this;
    }
});

itcast.fn.extend({
    mouseenter: function(type, callback) {
        return this.on("mouseenter", callback);
    }
});

itcast.each(("click,mouseenter,mouseleave,keydown,keyup").split(","), function(i, v) {
    itcast.fn[v] = function(callback) {
        return this.on(v, callback);
    };
});

1 普通事件绑定方式（如 onclick=..）：
    W3C标准：使用事件处理程序参数（event）IE9+ / Chrome / FF
    IE（8及以下版本）中   ：使用 window.event

2 addEventListener 和 attachEvent 都实现了事件参数event
    说明：即使是都实现了事件参数event，但是对象中的一些属性值还是存在差异，
          例如：which
    IE: 
    button 左1 中4 右2
    which 不存在

    Chrome: 
    button 左0 中1 右2
    which  左1 中2 右3

attachEvent的兼容性：
    支持：   IE6 - IE10
    不支持： IE11+（支持 addEventListener）

itcast("div").click(function(e) {
    e = e || window.event;
    // 获取事件类型
    alert(e.type);
});

itcast("div").click(function(e) {
    alert(e.which);
});

$("div").hover(function() {
    $(this).css("background", "#abc");
}, function() {
    $(this).css("background", "#fff");
});

itcast.fn.extend({
    hover: function(fn1, fn2) {
        return this.mouseenter(fn1).mouseleave(fn2);
    }
});

if(itcast.isFunction(selector)) {
    // window.onload = selector;
    window.addEventListener("load", selector);
}

var eventList = [];
window.onload = function() {
    for(var i = 0; i < eventList.length; i++) {
        eventList[i]();
    }
};

if(itcast.isFunction(selector)) {
    eventList.push(selector);
}

if(itcast.isFunction(selector)) {
    var oldFunc = window.onload;
    if(typeof oldFunc === "function") {
        window.onload = function() {
            selector();
            oldFunc();
        };
    } else {
        window.onload = selector;
    }
}

var fn = function() {
    alert(123);
};
dv.addEventListener("click", fn);
dv.removeEventListener("click", fn);