JS promise API gotchas

gotcha.js

function errorFunction(){
  return Promise.reject('Reject value.');
}
function goodFunction(error=false){
  return Promise.resolve('Resolved value.');
}

// Example 1. One level
goodFunction().then(function(ok){
  console.log('First "then" called. Value: ', ok);
}).catch(function(err){
  console.log('Outer "catch" called. Value: ', err);
});

errorFunction().then(function(ok){
  console.log('First "then" called. Value: ', ok);
}).catch(function(err){
  console.log('Outer "catch" called. Value: ', err);
});

// Example 2. Nested promises 
goodFunction().then(function(ok){
  console.log('First "then" called. Value: ', ok);

  // On ok, then is called
  goodFunction().then(function(ok){
    console.log('Inner "then" called. Value: ', ok);
  }).catch(function(err){
    console.log('Inner "catch" called. Value: ', err);
  });

  // On error, catch is called
  errorFunction().then(function(ok){
    console.log('Inner "then" called. Value: ', ok);
  }).catch(function(err){
    console.log('Inner "catch" called. Value: ', err);
  });
}).catch(function(err){
  console.log('Outer "catch" called. Value: ', err);
});

// Example 3. Nested promises not returned
goodFunction().then(function(ok){
  console.log('First "then" called. Value: ', ok);
  // No return but the other then is executed with value undefined
  goodFunction();

}).then(function(ok){
  console.log('Outer "then" called. Value: ', ok);
}).catch(function(err){
  console.log('Outer "catch" called. Value: ', err);
});

// Example 4. Nested promises returned
goodFunction().then(function(ok){
  console.log('First "then" called. Value: ', ok);
  // Has return, the other then is executed with value of goodFunction
  return goodFunction();

}).then(function(ok){
  console.log('Outer "then" called. Value: ', ok);
}).catch(function(err){
  console.log('Outer "catch" called. Value: ', err);
});