JavaScript native Promise execute callback on both results -

JavaScript native Promise execute callback on both results -

is there way execute callback on both results of promise object?

for illustration want create cleanup logic after execution of xhr request. need this:

var cleanup = function() { something.here(); } mylib.makexhr().then(cleanup,cleanup);

in jquery defered illustration can utilize method always():

mylib.makexhr().always(function() { something.here(); });

does promise back upwards this?

no, there none. discussed spec minimal. doesn't include bunch of other functionality. it's designed interoperate library promises , provide simple functionality.

here right polyfill of proposal made stefpanner.

moreover, disagree current deleted answers adding because they're doing wrong (as enumerable property - no fun). if ignore homecoming values , error state of returned promise. intended way extend native promises subclassing them, sadly, no browsers back upwards yet we'll have wait.

instead of messing native prototypes, should utilize different pattern:

opendb().then(foo).then(bar).finally(close).then(more);

is susceptible forgetting phone call close, if open 100 times in our app, forgetting close 1 time can still devastating. on other hand - can utilize disposer pattern promise libraries provide built in ourselves:

opendb(function(db){ homecoming foo(db).then(bar);// chain here }).then(more);

basically - pattern means instead of having opendb homecoming promise - have take function and homecoming promise, when function run, if returns promise wait promise resolve. looks like:

function opendb(withdb){ homecoming justopenwithoutcleanup(). then(withdb). then(clean, function(e){ clean(); throw e; }); // note rethrow }

javascript promise