为什么两次调用promise时RSVP Deferred都会产生错误

Question

Why RSVP Deferred produces an error when the promise is called twice?

It seems that there is a difference between deferred.promise.then().finally() and deferred.promise.then(); deferred.promise.finally() deferred.promise.then(); deferred.promise.finally() . Why?

 RSVP.on('error', function(reason) { console.log('Error: ' + reason); }); var deferred = RSVP.defer(); var deferred2 = RSVP.defer(); var deferred3 = RSVP.defer(); var promise3 = deferred3.promise; deferred.promise.then(function() { console.log('Resolved'); }, function() { console.log('Rejected'); }).finally(function() { console.log('Finally'); }); deferred2.promise.then(function() { console.log('Resolved2'); }, function() { console.log('Rejected2'); }); deferred2.promise.finally(function() { console.log('Finally2'); }); promise3 = promise3.then(function() { console.log('Resolved3'); }, function() { console.log('Rejected'); }); promise3.finally(function() { console.log('Finally3'); }); deferred.reject('Reject!'); deferred2.reject('Reject2!'); deferred3.reject('Reject3!'); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/rsvp/4.8.1/rsvp.js"></script> 

EDIT: I found out how to fix the issue. See the Deferred3 in the code.

Answer 1

I found that promise.then() (and other methods) returns a modified promise so you have to chain the then , finally , catch ... methods or you have to save the promise each time.

 RSVP.on('error', function(reason) { console.log('Error: ' + reason); }); var deferred = RSVP.defer(); var promise = deferred.promise; promise = promise.then(function() { console.log('Resolved'); }, function() { console.log('Rejected'); }); promise.finally(function() { console.log('Finally'); }); deferred.reject('Reject!'); 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/rsvp/4.8.1/rsvp.js"></script>