feat(Core): fix #910, add a flag to allow user to check duplicate Zone error.

[JiaLiPassion]

fix #910.

add a flag, __zone_symbol__forceDuplicateZoneCheck to let user choose whether to throw error when load duplicate zone.js.
By default, if the global['Zone'] is from zone.js, no error will be thrown, and if the flag is set to trure, then we will throw the error.

sometimes user may not want this Zone already loaded error.
For example,
we have two web pages, page1 includes zone.js, page2 doesn't.
and the 1st time user load page1 and page2, everything work fine,
but when user load page2 again, error occurs because global['Zone'] already exists.
so we add a flag to let user choose whether to throw this error or not.

[chandramuralis]

@JiaLiPassion Any idea when this fix will be released?

[RichardZandi]

@JiaLiPassion there is a similar issue, i believe, with importing native-shim in polyfills when an Angular Element tries to consume another Angular Element. It'd be great if the forthcoming zone fix would address that issue as well. Thank you.

[JiaLiPassion]

@RichardZandi, sure, thank you for the information.
@chandramuralis, I am not sure when will release, please wait for a while...

[benoitjchevalier]

Do we have any update on when this will release? This prevents using angular elements in another angular app

[JiaLiPassion]

@benoitjchevalier, I am not sure about the release date, you can use this branch for test by updating your package.json.

"zone.js": "git://github.com/JiaLiPassion/zone.js#duplicate-patch-dist"

[benoitjchevalier]

@JiaLiPassion thanks for the tips, we nicked your fix from a zip file you posted in another issue and added it to our project but pointing to the branch will be cleaner. It solves our problem 👍 .

However we're planning on distributing a packaged js file with a bunch of angular element, so we don't have control over whether consuming angular application will have this fix, hence eagerly waiting for it :)

Thank you for your work!

[aaaa0441]

I need to subscribe myself to this issue, waiting for a release of the fix.

[Saphirim]

Also waiting for an official release within Angular...

[liorwohl]

@JiaLiPassion solutions works for me. how is angular 7.0.0 released without this?

[hyahyaoui]

@JiaLiPassion thanks for the tips, we nicked your fix from a zip file you posted in another issue and added it to our project but pointing to the branch will be cleaner. It solves our problem 👍 .

However we're planning on distributing a packaged js file with a bunch of angular element, so we don't have control over whether consuming angular application will have this fix, hence eagerly waiting for it :)

Thank you for your work!

@benoitjchevalier do you have a link for the zip please ? thanks

[benoitjchevalier]

@hyahyaoui I ended up forking and manually integrating one of the PR that hasn't been merged yet and rebuilt it: "zone.js": "https://github.com/benoitjchevalier/zone.js.git#duplicate"
@JiaLiPassion also released another dist on a branch of his, probably best to use that (don't think that includes the duplicate check PR if you need it): "zone.js": "git://github.com/JiaLiPassion/zone.js#release-20181029"

[nakshay]

is this fix released, I need to fix similar issue.

[JiaLiPassion]

@nakshay, yes, this is released, you can check it with zone.js 0.9.0.