In Node.js, is there a syntax to just have an inline block which returns?

In (say) Swift, you can have an inline block with a return, anywhere you like in code, for example:

let x = 3
let y = 4
let z = {
  blah
  blah
  blah
  return blah blah
}()
let p = 12
let q = 13

or say:

ra.append( // (Swift equivalent of push)
   {
        blah
        blah
        return blah
   }()
)

The best I can do on Node.js (this is server side only, if it matters) is:

ra.push(
    (() => {
        x = 3
        y = x * 12
        return y
    })()
)

Is there a better way?