jquery mobile 打开panel报错：Uncaught Error: cannot call methods on panel prior to initialization; attempted to call method 'open'

今天在使用jQuery mobile panel时遇到问题

按照API，打开panel应该用：$( "#idofpanel" ).panel( "open" );

可是我这么写之后一直报错：Uncaught Error: cannot call methods on panel prior to initialization; attempted to call method 'open'，大概意思是panel未经实例化不能调用open

解决方案为：$( "#idofpanel" ).panel().panel( "open" );

前一个panel()用来实例化，第二个用来打开open