checkInventory, processPayment and shipOrder are all functions that return promises.

Codecademy tells me that this should work:

checkInventory(order)
.then((resolvedValueArray) => {
 return processPayment(resolvedValueArray);
})
.then((resolvedValueArray) => {
  return shipOrder(resolvedValueArray);
})
.then((successMessage) => {
  console.log(successMessage);
})
.catch((errorMessage) => {
  console.log(errorMessage);
});

But that this should not work:

checkInventory(order)
.then(processPayment)
.then(shipOrder)
.then((successMessage) => {
  console.log(successMessage);
})
.catch((errorMessage) => {
  console.log(errorMessage);
});

However both pieces of code work and output the same thing. I am very confused!

Would the two examples give different output under different conditions? Why?

The exercise gives this code as an example:

firstPromiseFunction()
.then((firstResolveVal) => {
  return secondPromiseFunction(firstResolveVal);
})
.then((secondResolveVal) => {
  console.log(secondResolveVal);
});

And says, regarding it:

In order for our chain to work properly, we had to return the promise secondPromiseFunction(firstResolveVal). This ensured that the return value of the first .then() was our second promise rather than the default return of a new promise with the same settled value as the initial.