A quick promise chaining demonstration.

promises.js

// not chaining
asyncFunction().then(data => {
  asyncFunction(data).then(data2 => {
    asyncFunction(data2);
  }).catch(console.error);
});

// chaining
asyncFunction.then(data => {
  return asyncFunction(data);
}).catch(console.error).then(data2 => {   // this catch statement would catch all previously chained promises
  return asyncFunction(data2);
});

function asyncFunction(say)  {
  return new Promise(resolve => {
    setTimeout(() => {
      resolve(say || 'async complete');
    }, 1000);
  });
}