Check if a property exist for an object

Hopefully, I understand what you mean now. Try this,

function CheckProperty()
 {
     const Name = {
         Firstname: "SmartBear"
     }
     
     Log.Message(Name.Firstname);
     Log.Message(Name.hasOwnProperty("Firstname")); // true
     Log.Message(Name.hasOwnProperty("Surname"));   // false
 }

Use "hasOwnProperty()"