Doesn't work in IE11

[altano]

It looks like MutationObserver isn't firing in IE11. Paste this into the console:

ES6Promise.Promise.resolve("hello").then(function(v){console.log(v);});

This won't fire. If I then paste this:

setTimeout(function(){},1);

Then both the setTimeout event AND the .then() callback function get called. This must be some kind of IE bug? I couldn't find anyone reporting it though so I must be mistaken?

[altano]

Also worth noting: $$asap$$flush WILL get called immediately if I set a breakpoint in es6-promise on the line that changes node.data. If I disable the breakpoint, $$asap$$flush doesn't get called. Bizarre, right?

[stefanpenner]

Woah. Maybe a mutation observer related quirk? This seems gnarly. I'll take a look in the AM

[edoloughlin]

Any update on this?

[stefanpenner]

Sorry this slipped my queue I'll take a look today crap, i let this slip. I need to finish a talk today, I will add a sticky note to my desk to dig in... This appears extremely crappy, my apologies for letting it linger.

[stefanpenner]

I am unfortunately unable to reproduce this issue. :(
this is very strange, investigating.

[stefanpenner]

So, this is interesting.

this only appears to be an issue, when using the console. The same code outside of the console works as expected. Hence why no app I work on demonstrates issues on IE11.

It appears MutationObserver changes just queue up when the console is open. They flush when a setTimeout occurs. But when debugging everything appears fine.

[stefanpenner]

Also, if you merely "click" anywhere in the page, the queue flushes..

[stefanpenner]

MessageChannel appears to work correctly... We could force IE11 to use this instead.

[stefanpenner]

I suspect the resolution is to:

1. switch to MessageChannel
2. report the bug upstream.

[JF10R]

Any update on the issue? You're saying it's related to the console... do you mean simply having the console/dev tools opened, or using the console javascript object (console.log()) ?

I'm facing a similar issue with the promise not resolving correctly on IE11 and I'm wondering if this is the problem.

[stefanpenner]

This is only the result of triggering a change from the console. So when a dev attempts to debug a promise via the developer console. They must tap the web view to flush the changes. This is clearly and ie11 bug. Although to save the sanity of dev, we may want to migrate to message channel for async.

If the change did not originate from the console, I have very high confidence that it is not a bug with this library. As its extensive test suite runs without issue on ie11.

To summarize, this does not affect normal app usage. Only some circumstances in the ie11 dev console do issues arise.

[stefanpenner]

So we have a choice to make, we can revert to use the wrong async in IE11, or deal with it. Both options really do suck..

cc @jdalton I tried to report this but with IE11, but the login sequence kept erroring with me. Do you have any thoughts or suggestions here?

cc @domenic Also curious if you have some advice. Let me know if i should provide more context.

[domenic]

I would say deal with it; devs should be deving for Edge hopefully. Maybe add a loud warning.

[stefanpenner]

Maybe add a loud warning.

sniff the version and console.log something ?

if your seeing this, please call your local M$ representative and complain violently.

[domenic]

Yeah or just in the readme. But that is probably better.

[JF10R]

Either solution would probably fit everyone's needs. IE11 will be forgotten soon enough with Edge being pushed out so much.

[stefanpenner]

I can likely also give a function to force the lib to some other async. Something the dev can run right after seeing the message so debugging isn't horrible

[jdalton]

FWIW I can't repro the issue on Win 10 IE 11 using http://static.iamstef.net/es6-promise/ or ES6Promise.Promise.resolve("hello").then(function(v){console.log(v);});. Both log.

Also confirmed it works on my Win 10 VM and https://remote.modern.ie/ too.
Works as in cannot repro bug.

[stefanpenner]

Works as in cannot repro bug.

If this is accurate, then awesome. Maybe some patch addressed this.

I am going to close the issue, as @jdalton someone who works on IE/chakra is unable to reproduce. I would say the problem is fixed.

If someone can demonstrate another scenario that fails we will gladly reopen.

@jdalton / @domenic thanks for your help