node.js - Bluebird - how to propagate errors in nested promise -

promisea().then(function(){     promiseb().catch(function (e) {         throw e;     }) }).catch(function (e) {     // want exceptions thrown in nested promise chain end here. }) 

how exceptions nested promises bubble parent promise?

use return keyword,

your code can simplified as:

promisea().then(function(){     return promiseb(); }).catch(function (e) {     // want exceptions thrown in nested promise chain end here. }) 

edit:

not sure if right way, if promise cancellation involved , want bubble error flow, can wrap promise in custom promise never resolves throws error( if happens):

promisea().then(function(){     var mypromise = promiseb().then...;     return new promise(function(resolve, reject){       mypromise.catch(reject)     }) }).catch(function (e) {     // want exceptions thrown in nested promise chain end here. })