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| function createAsyncFunction(fn) { | |
| return function () { | |
| var gen = fn.apply(this, arguments); | |
| return new Promise(function (resolve, reject) { | |
| function step(key, arg) { | |
| try { | |
| var info = gen[key](arg); | |
| var value = info.value; | |
| } catch (error) { | |
| reject(error); | |
| return; | |
| } | |
| if (info.done) { | |
| resolve(value); | |
| } else { | |
| return Promise.resolve(value).then(function (value) { | |
| step("next", value); | |
| }, function (err) { | |
| step("throw", err); | |
| }); | |
| } | |
| } | |
| return step("next"); | |
| }); | |
| }; | |
| } |
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Hello Jake!
I don't even know how I got to this function (I've got dozens of tabs open while I research asynchronous javascript). At first I found it quite cryptic, but I took figuring it out as a challenge.
So after a few days tinkering with it I believe It takes a generator function, then returns a function that accepts arguments that might be used by such generator function to craft an Iterable. Then it creates said iterable (as a generator object), then returns a pending promise that will start an iteration sequence and only settle when an iteration throws an error, returns a rejected promise, or is the last one.
Now here's the motivation for this comment: I believe the return statements on lines 23 and 16 are both unnecessary/inert. The reasoning being:
For line 23:
For line 16:
TL;DR: For didactic purposes I removed the return statements in lines 16 & 23, kept the returned expressions. Code worked the same.
I don't even think you'll be bothered with this, but still serves me as an exercise, though.
Loved your event loop talk in JSConf.Asia!
Cheers