嗨,我想在节点js中定义以下结构
var packetHeader = new Struct()
.word16Ule('packetLength')
.word8Ube('cmd')
.word8Ube('version')
.word8Ube('checkSum')
.word32Ule('token')
.word32Ule('random')
.word16Ule('magicNumber')
.word16Ule('lengthOfStationId')
.chars('text1', <lengthOfStationId>);
如何将text1字段定义为其上方定义的字段长度?