Node.js 显示类型错误：无法读取未定义的属性

Question

RV =(typeof (myresult.CDF.UTILITYTYPE.D2.INSTPARAM[0].VALUE !== 'undefined')) ? myresult.CDF.UTILITYTYPE.D2.INSTPARAM[0].VALUE : 'NA';
                                                             

in the above code i want to get the value, if the key does not exists it should take 'NA' but iam getting below error

Error : - TypeError: Cannot read properties of undefined (reading 'INSTPARAM')

Answer 1

myresult.CDF.UTILITYTYPE.D2?.INSTPARAM[0].VALUE?? 'NA';

using the option chaining.