HarmonyOS关于UI组件的属性配置是否为可选或者是否有默认值可以查看

export class NVTextView extends  VVBaseNode{ 
  text:string|undefined = undefined 
  textSize: number = 0 
  textColor: ResourceColor = Color.Black 
  textStyle: BKTextStyle = BKTextStyle.Normal 
  fontName:string|undefined = undefined 
} 
@Builder 
function buildTextViewLabel(node: NVTextView) { 
  Text(node.text) 
    .fontFamily(node.fontName)  //其实和系统要求的类型不一致，怎么判断了node.fontName有值再设置这个属性呢 
    .fontSize(node.textSize) 
    .fontColor(node.textColor) 
    .maxLines(node.maxLines) 
}