javascript - ES6 Promise automatic post-processing / cloning results -

i have situation building data layer based on es6 js promises fetch data network. caching promises internally url.

everything seems working fine except 1 thing. want ensure data coming out of network layer copy/clone of data retrieved network , not want everywhere in client code implements promise's handlers.

i set handler automatically gets copy of cached data.

to add twist this, configurable on url basis inside data layer promises post-processing copy while others return raw result.

can suggest proper implementation accomplish this? should mention new copy of original raw result each time new client asks it.

the current simplified pseudo implementation looks

getcacheddata(url){    if (cache[url]) {      return cache[url];    } else {      var promise = new promise(function(resolve,reject){           var data = ...ajax get...;           resolve(data);      });      cache[url] = promise; }  getcacheddata(url).then(result=>{    here want result copy of data resolved original promise with. }); 

structure this:

function retrievecopieddata () {     // getdatafromserver original promise     return getdatafromserver().then(function (value) {         // use library of choice copying object.         return copy(value);     })} } 

this means consumers of retrievecopieddata receive value returned retrievecopieddata's then() handler.

retrievecopieddata().then(function (value) {     // value copy returned retrievecopieddata's handler }) 

you can add conditional logic retrievecopieddata see fit.