Sorry but that is not how Promises work. You compose the entire promise chain in one "tick" and then you start execution of the entire chain.
I will try to write you an over simplification of the concept... Hang on :) On Fri, Sep 7, 2018 at 9:35 PM Peter Jaszkowiak <[email protected]> wrote: > > No, it doesn't make any sense. > > Do you not see the impossibility of this? If you have a promise `a`: > > You call `b = a.then(one).finally(done)` > > `b` is a promise. You can't have the thread waiting forever for every > possible descendent to be added before executing the `done` function. There > may even be none. > > On Fri, Sep 7, 2018, 13:27 Jon Ronnenberg <[email protected]> wrote: >> >> I'm suggesting that finally is the last function to be executed. So >> the chain is, then().then().then().catch().finally(), regardless of at >> what time then or catch is added to the Promise chain. >> Like try->catch->finally with a callback but without a callback. Does >> it make sense? >> On Fri, Sep 7, 2018 at 9:24 PM Peter Jaszkowiak <[email protected]> wrote: >> > >> > There are plenty of ways of doing what you need without changing the >> > behavior of finally. Are you suggesting that calling finally make it so >> > any other then or catch call just not execute? And are you also suggesting >> > that this should climb up the chain of promises? >> > >> > On Fri, Sep 7, 2018, 13:16 Jon Ronnenberg <[email protected]> wrote: >> >> >> >> I know I am late to the game and that Promise.prototype.finally is >> >> already in stage 4 but(!). >> >> >> >> It's just not very useful to have a final function when it's not the >> >> final function to run. If it's suppose to be for cleanup, then the >> >> current implementation is seriously lacking usefulness. >> >> >> >> Consider the following example: >> >> >> >> <audio >> >> class="i-am-the-element" >> >> autoplay="autoplay" >> >> controls="controls"> >> >> <source type="audio/mp3" >> >> src="http:\/\/play.dogmazic.net\/play\/index.php?type=song&oid=22951&uid=-1&name=Black%20poetry%20-%20Aime-.mp3"> >> >> </audio> >> >> <script> >> >> class Demo { >> >> constructor (element) { >> >> this.node = element >> >> } >> >> destroy () { >> >> return new Promise(resolve => { >> >> // do something or nothing >> >> resolve() >> >> }).finally(() => { >> >> // schedule for DOM removal >> >> this.node = null >> >> }) >> >> } >> >> } >> >> >> >> const demo = new Demo(document.querySelector('.i-am-the-element')) >> >> >> >> setTimeout(() => { >> >> demo.destroy().then(() => { >> >> // will throw an error because finally was run before >> >> demo.node.pause() >> >> }).catch(console.error) >> >> }, 3000) >> >> </script> >> >> >> >> One grand idea about promises is to delegate and compose asynchronous >> >> functions, but the current implementation can not be used to for code >> >> delegation. >> >> >> >> From the top of my head the only way to have consumer code, tap into an >> >> execution process is to use callbacks which is what Promises were suppose >> >> to help alleviate. >> >> >> >> <audio >> >> class="i-am-the-element" >> >> autoplay="autoplay" >> >> controls="controls"> >> >> <source type="audio/mp3" >> >> src="http:\/\/play.dogmazic.net\/play\/index.php?type=song&oid=22951&uid=-1&name=Black%20poetry%20-%20Aime-.mp3"> >> >> </audio> >> >> <script> >> >> class Demo { >> >> constructor (element) { >> >> this.node = element >> >> } >> >> destroy (callback) { >> >> // do something or nothing >> >> try { >> >> callback() >> >> } finally { >> >> // schedule for DOM removal >> >> this.node = null >> >> } >> >> } >> >> } >> >> >> >> const demo = new Demo(document.querySelector('.i-am-the-element')) >> >> >> >> setTimeout(() => { >> >> demo.destroy(() => { >> >> demo.node.pause() >> >> }) >> >> }, 3000) >> >> </script> >> >> >> >> If at all possible, please amend to the spec before it's too late! ... or >> >> just drop it. >> >> >> >> My current use-case is that I work with PSPDFKit and can not get DOM >> >> access but rather schedule removal of DOM nodes via their API, but I can >> >> pause audio/video - just not using Promise.prototype.finally as it is >> >> currently envisioned. >> >> >> >> Regards, Jon >> >> >> >> PS. Tested in Firefox 63.0b3 and Safari 11.1.2 >> >> Here is a polyfill if you need: >> >> https://cdn.polyfill.io/v2/polyfill.minify.js?features=Promise.prototype.finally&flags=gated >> >> >> >> _______________________________________________ >> >> es-discuss mailing list >> >> [email protected] >> >> https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
