javascript - 未捕获的类型错误：对象 [object Object] 没有方法“selectedBases”

Question

任何想法我做错了什么？因为我收到错误消息Uncaught TypeError: Object [object Object] has no method 'selectedBases' 下面是我的代码

this.selectedBases = ko.observable();
        this.selectedBases.subscribe(function (options) {
             if(options.length >0){
                if (options.find('select_all')) {
                    self.selectedBases(options.intersect('select_all'));
                } 
            } 
        });