javascript - Flatter calls using promises: avoiding callbackception -

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this question has answer here:

i have found following use case while working promises. writing coffeescript concision reading javascript developers should straight forwards

getusername().then (username) ->   getrelatedcompany(username).then (relatedcompany) ->     registerconnexion(username, relatedcompany)

in above request depend of above results of previous ones. what's proper way solve this:

getusername().then (username) ->   getrelatedcompany(username) .then (relatedcompany) ->   # in example, username undefined here there's less callbackception   registerconnexion(username, relatedcompany)

edit: using bluebird promise library.

you can use promises proxies represent values:

username = getusername() company = username.then(getrelatedcompany) // assuming promise lib, otherwise shim .spread of nest once connexion = promise.all([username, company]).spread(registerconnexion)

in bluebird, simpler , becomes:

username = getusername() company = username.then(getrelatedcompany) connexion = promise.join(username, company, registerconnexion);

since .join designed use case in mind.


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