How to add optional chaining to JSON object?

Question

I am trying to compare a value within a JSON object with a variable:

if (resp.userdetails.name == username) {
// do something
}

The problem is that not all resp objects have userdetails, so I get this error message sometimes:

Cannot read properties of undefined (reading 'name')

I have tried to use ? to say it might be optional (or not exist):

if (resp.userdetails?.name == username)

But I get an Unexpected token error in that case.

Can someone please tell me how I can update my if statement to say userdetails may not always be in the response, but if it is, then check name is equal to username?

Answer 1

Either:

• Use a JS engine which supports optional chaining
• Use a tool like Babel to transpile your JS from a modern version of the language to an older one which doesn't support optional chaining
• Manually test for the object existing before you try to read a property from it

if (resp.userdetails && resp.userdetails.name == username)