js 对象声明问题........

if ( typeof(mp) == "undefined" ) {
    var mp = {};
}
mp.random = function(){ return Math.floor( Math.random() * 100 );
}
//...代码省略
 
mp.edit = {}; // IE下这里报错说缺少标示F,如果调用mp.random()提示mp未定义
吧edit代码块注释掉就正常了，但在FF、chrome下又正常 求解？
mp.edit.createEdit = function ( obj, options ) {
    var myEdit = obj.attr( 'id' );
    KindEditor.ready( function ( K ) {
        myEdit = K.create( obj, options );
    }); return myEdit;
}