onshow调用selectComponent报错

错误样例: this.selectComponent is not a function. (In 'this.selectComponent("#SharePosterImage")', 'this.selectComponent' is undefined);at "pages/detail/detail" page lifeCycleMethod onShow function

代码样例：

if (this.selectComponent('#SharePosterImage')) {         this.selectComponent('#SharePosterImage').cancelModal() }