In a Promise, what's the difference between using catch and the 2nd argument of then? [duplicate]

Answer 1

.catch(foo) is equal to .then(undefined, foo)

But there is a difference between your code samples:

funcThatReturnsAPromise()
  .then(() => { /* success case of funcThatReturnsAPromise */ })
  .catch(() => { /* both fail case of funcThatReturnsAPromise 
                     and fail case of "then" function */ });


funcThatReturnsAPromise()
  .then(() => { /* success case of funcThatReturnsAPromise */ }, 
        () => { /* fail case of funcThatReturnsAPromise */ });