Extjs 中使用单例模式

返回一个匿名函数，使得没有办法使用new来进行实例化，这是javascript单例模式的一种实现方式（类似于java的单例）。匿名函数对于funtion内部的局部变量匿名函数是可以调用的，但外部函数是不能访问的，这样是很好的对数据进行保护，相当于实现了private

Ext.example = function(){
    var msgCt;
    function createBox(t, s){
        return ['<div class="msg">',
                '<div class="x-box-tl"><div class="x-box-tr"><div class="x-box-tc"></div></div></div>',
                '<div class="x-box-ml"><div class="x-box-mr"><div class="x-box-mc"><h3>', t, '</h3>', s, '</div></div></div>',
                '<div class="x-box-bl"><div class="x-box-br"><div class="x-box-bc"></div></div></div>',
                '</div>'].join('');
    }
    return {
        msg : function(title, format){
            if(!msgCt){
                msgCt = Ext.DomHelper.insertFirst(document.body, {id:'msg-div'}, true);
            }
            msgCt.alignTo(document, 't-t');
            var s = String.format.apply(String, Array.prototype.slice.call(arguments, 1));
            var m = Ext.DomHelper.append(msgCt, {html:createBox(title, s)}, true);
            m.slideIn('t').pause(1).ghost("t", {remove:true});
        },

        init : function(){
            var t = Ext.get('exttheme');
            if(!t){ // run locally?
                return;
            }
            var theme = Cookies.get('exttheme') || 'aero';
            if(theme){
                t.dom.value = theme;
                Ext.getBody().addClass('x-'+theme);
            }
            t.on('change', function(){
                Cookies.set('exttheme', t.getValue());
                setTimeout(function(){
                    window.location.reload();
                }, 250);
            });

            var lb = Ext.get('lib-bar');
            if(lb){
                lb.show();
            }
        }
    };
}();