ECMAScript Promise chains

案例： 通过 getData()方法获取初始数据， 方法返回后调用下一相应方法 getSpecInfo()

getData():void{  
  mBusinessBase.call(MProcurementServletKey.SearchGBMallItemDetail)  
  .then((json:UJsonRespond)=>{  
    ...do something  
    return this.getSpecInfo();  
  })  
  .then((json:UJsonRespond)=>{  
    ...do something 
  });  
}  
    
getSpecInfo():Promise<UJsonRespond>{  
  return mBusinessBase.call(MProcurementServletKey.SearchItemPriceAndQuantityInfo);   
}