NodeJS: shorter way to create a conditional property in an object than self-invoked function? (either ES5 or ES6)

Is there a shorter way to express the following? (either ES5 or ES6)

res.cookie('abc', 'xyz', (function(){
            var obj = {maxAge: 900000, httpOnly: true };
            if (process.env.NODE_ENV==="production"){
                obj.secure = true;
            }
            return obj;
        })());

ES6 offers the Object.assign method, which you might be able to use like so:

var obj = Object.assign(
  {
    maxAge: 900000,
    httpOnly: true,
  },
  process.env.NODE_ENV === "production"
    ? { secure: true }
    : {}
)

That will ensure that the key secure is not even present in the final object if the environment isn't production. If you're okay with the key being there, but with a value of false, then:

var obj = {
  maxAge: 900000,
  httpOnly: true,
  secure: process.env.NODE_ENV === "production",
}

will suffice.

In even newer versions of ECMAScript, you have access to object destructuring using the ... operator. So you could turn the first snippet into a more concise version:

var obj = {
  maxAge: 900000,
  httpOnly: true,
  ...process.env.NODE_ENV === "production"
    ? { secure: true }
    : {},
}