How to add optional chaining to JSON object?-CodePudding

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?

CodePudding user response：

Either:

Use a JS engine

Eg:-

  var _ = require("lodash");

var data = [
  { userdetails: { name: "d" } },
  {},
  { userdetails: {} },
  { userdetails: { name: "d" } },
];

for (i = 0; i < data.length; i  ) {
  var resp = data[i];
  if (_.get(resp, "userdetails.name") == "d") {
    //   if (resp.userdetails && resp.userdetails.name == "d") {    use without loadlash
    console.log("Success");
  } else {
    console.log("failed");
  }
}

Here loadash is super complex. But you can use this to avoid runtime errors. Below both expressions get the same result

   resp.userdetails && resp.userdetails.name == "d"

                        ===

         _.get(resp, "userdetails.name") == "d"