parseServerResponse.js

function mockServerCall () {
  return new Promise((resolve, reject) => {
    setTimeout(() => {
      resolve({
        'status': 200,
        'content-type': 'application/json',
        'data' : {
          dataOfInterest: 42
        }
      })
    }, 250)
  })
}

mockServerCall()
  .then(({data: { dataOfInterest = 100 }}) => {
    console.log(dataOfInterest) // 42 (but would default to 100)
  })