Promise vs Observable in JavaScript
Promises provide a single future value while Observables provide any number of future values.
Observables are not a superset of Promises as they are inifinite lists that
can be composed using various operators such as map
, filter
or reduce
.
Observables can be cancelled while Promises cannot be cancelled.
Streams in Node.js are not observables.
Promises return a value only once while Observables may return a value more than once.