Use Promise Proxy ( Proxise ) for easily resolving promises outside the Promise function.
somefunc = proxise (params) -> if (ready) => return Promise.resolve('some value')
somefunc params .then (v) -> /* doing something ... */
somefunc.resolve 'some value'
Proxise use the return value inside the proxise function to decide how things work:
- return promise - then the promise will be used when somefunc is called.
- otherwise - proxise create a new Promise object and enqueues it until somefunc.resolve is called. When somefunc.resolve is called, all queued promises will be resolved immediately.
Proxise is quite helpful for resolving promise outside the promise function, for example, by user interaction:
until-user-click = proxise ->
until-user-click!then -> console.log \user-clicked.
document.body.addEventListner \click, -> until-user-click.resolve!
proxise is also useful for waiting until sutff gets intiailized. In this scenario, we need:
- wrapped function is run for at most once.
- every invocation of the wrapped function will be resolved after successful run of the wrapped function.
You can simply use proxise.once to achieve this effect.
For example,
init = proxise.once -> alert("this alert shall only popup once.")
is equivalent to
_init = -> alert("this alert shall only popup once.")
init = proxise ->
if init.inited => return Promise.resolve!
if init.initing => return
Promise.resolve!
.then -> _init!
.finally -> init.initing = false
.then -> init.inited = true
.then -> init.resolve!
.catch -> init.reject it
Additionally, you can ask the inited function to return a specific value by the second option:
init = proxise.once (->), (-> "return me")
MIT