一个闭包和原型继承的例子

(function(window, jQuery, undefined) {

var HTMLS = {
    ovl: '<div class="J_WinpopMask winpop-mask" id="J_WinpopMask"></div>' + '<div class="J_WinpopBox winpop-box" id="J_WinpopBox">' + '<div class="J_WinpopMain winpop-main"></div>' + '<div class="J_WinpopBtns winpop-btns"></div>' + '</div>',
    alert: '<input type="button" class="J_AltBtn pop-btn alert-button" value="确定">',
    confirm: '<input type="button" class="J_CfmFalse pop-btn confirm-false" value="取消">' + '<input type="button" class="J_CfmTrue pop-btn confirm-true" value="确定">'
}

function Winpop() {
    var config = {};
    this.get = function(n) {
        return config[n];
    }

    this.set = function(n, v) {
        config[n] = v;
    }
    this.init();
}

Winpop.prototype = {
    init: function() {
        this.createDom();
        this.bindEvent();
    },
    createDom: function() {
        var body = jQuery("body"),
            ovl = jQuery("#J_WinpopBox");

        if (ovl.length === 0) {
            body.append(HTMLS.ovl);
        }

        this.set("ovl", jQuery("#J_WinpopBox"));
        this.set("mask", jQuery("#J_WinpopMask"));
    },
    bindEvent: function() {
        var _this = this,
            ovl = _this.get("ovl"),
            mask = _this.get("mask");
        ovl.on("click", ".J_AltBtn", function(e) {
            _this.hide();
        });
        ovl.on("click", ".J_CfmTrue", function(e) {
            var cb = _this.get("confirmBack");
            _this.hide();
            cb && cb(true);
        });
        ovl.on("click", ".J_CfmFalse", function(e) {
            var cb = _this.get("confirmBack");
            _this.hide();
            cb && cb(false);
        });
        mask.on("click", function(e) {
            _this.hide();
        });
        jQuery(document).on("keyup", function(e) {
            var kc = e.keyCode,
                cb = _this.get("confirmBack");;
            if (kc === 27) {
                _this.hide();
            } else if (kc === 13) {
                _this.hide();
                if (_this.get("type") === "confirm") {
                    cb && cb(true);
                }
            }
        });
    },
    alert: function(str, btnstr) {
        var str = typeof str === 'string' ? str : str.toString(),
            ovl = this.get("ovl");
        this.set("type", "alert");
        ovl.find(".J_WinpopMain").html(str);
        if (typeof btnstr == "undefined") {
            ovl.find(".J_WinpopBtns").html(HTMLS.alert);
        } else {
            ovl.find(".J_WinpopBtns").html(btnstr);
        }
        this.show();
    },
    confirm: function(str, callback) {
        var str = typeof str === 'string' ? str : str.toString(),
            ovl = this.get("ovl");
        this.set("type", "confirm");
        ovl.find(".J_WinpopMain").html(str);
        ovl.find(".J_WinpopBtns").html(HTMLS.confirm);
        this.set("confirmBack", (callback || function() {}));
        this.show();
    },
    show: function() {
        this.get("ovl").show();
        this.get("mask").show();
    },
    hide: function() {
        var ovl = this.get("ovl");
        ovl.find(".J_WinpopMain").html("");
        ovl.find(".J_WinpopBtns").html("");
        ovl.hide();
        this.get("mask").hide();
    },
    destory: function() {
        this.get("ovl").remove();
        this.get("mask").remove();
        delete window.alert;
        delete window.confirm;
    }
};

var obj = new Winpop();
window.alert = function(str) {
    obj.alert.call(obj, str);
};
window.confirm = function(str, cb) {
    obj.confirm.call(obj, str, cb);
};

})(window, jQuery);