promise.finally.with.finally.js

const promise = new Promise(resolve => {
  setTimeout(()=>resolve('success'));
});

const startOperation = () => { console.log('start'); };
const finishOperation = () => { console.log('finish'); };

startOperation();

promise
.then(
  result => { console.log('success:', result);},
  error => { console.log('error:', error);}
)
.finally(finishOperation);