Are there differences between .then(functionReference) and .then(function(value){return functionReference(value)})?

Question

Given a named function utilized to handle a Promise value

function handlePromise(data) {
  // do stuff with `data`
  return data
}

Answer 1

There is no difference, function(x){return f(x)} === f.

For more info, you may want to read about eta-conversion in lambda calculus.