'WeakMap' is undefined

[rafaelmaiolla]

The commit in this revision b44664e has caused the problem.

MutationOberserve code requires the WeakMap to be defined.

[addyosmani]

Can you provide details about what build (full or -lite) and browser you are experiencing this issue with?

[rafaelmaiolla]

It is the lite build on IE9, but will probably have the same issue on IE10.

The revision I added in the first comment may not be the problem. I think the problem actually started in this one a49aaee

[addyosmani]

We don't officially support IE9, per the browser compatibility matrix in the README. Are you able to repro this issue in IE10?

[rafaelmaiolla]

The problem is reproducible on IE10 too.

[adidahiya]

I'm seeing this problem as well, but only when running mocha tests via phantomJS. Simply including webcomponents-lite.js throws the error Can't find variable: WeakMap in phantom. Downgrading to v0.5.4 fixed the problem.

[mereskin-zz]

Same here, in Safari 7 on iOs 7

[Jeff17Robbins]

build-lite.json pulls in MutationObserver (which uses WeakMap) before it pulls in HTMLImport (which defines WeakMap on browsers that lack it.)

The prebuilt webcomponents-lite.js version 0.5.5 (available through a link on the homepage https://github.com/webcomponents/webcomponentsjs/archive/0.5.5.zip ), as a result of this build order, has this problem of using WeakMap at line 55 before defining it starting at line 353.

This commit seems to have caused this breaking change:
b44664e

However, if MutationObserver now really does need to be ahead of HTMLImport, then perhaps we need WeakMap pulled in as part of build-lite.json and have HTMLImport stop pulling it in?

https://github.com/webcomponents/webcomponentsjs/blob/master/src/WebComponents/build-lite.json
[
"build/boot.js",
"../MutationObserver/MutationObserver.js",
"../HTMLImports/build.json",
"../CustomElements/build.json",
"../Template/Template.js",
"unresolved.js"
]

[paulie4]

Since HTMLImports/build.json and CustomElements/build.json are both including their "../WeakMap/WeakMap.js" dependency, why don't you move the "../MutationObserver/MutationObserver.js" dependency into each of those and out of build-lite.json? Of course, it will need to go after "../WeakMap/WeakMap.js".

[paulie4]

I just noticed that ShadowDOM has its own MutationObserver.js polyfill (used by the non-lite webcomponents), so the "../MutationObserver/MutationObserver.js" dependency should not move into the common HTMLImports/build.json and CustomElements/build.json files. I tested adding the "../WeakMap/WeakMap.js" dependency directly into src/WebComponents/build-lite.json, right before "../MutationObserver/MutationObserver.js", and it correctly doesn't affect anything else except for fixing this issue by moving the WeakMap polyfill code before the dependent MutationObserver polyfill code. This is a simple change, but if you'd like, I could create a pull request for it. src/WebComponents/build-lite.json would look like this:

[
  "build/boot.js",
  "../URL/URL.js",
  "../WeakMap/WeakMap.js",
  "../MutationObserver/MutationObserver.js",
  "../HTMLImports/build.json",
  "../CustomElements/build.json",
  "../Template/Template.js",
  "unresolved.js"
]

[TimvdLippe]

Thanks for the issue. It has been a great while since this issue was opened. Sadly, this issue misses a live reproduction with the most recent version of the webcomponents polyfill for us to be able to debug and potentially fix. Versions 1 of the polyfills fix a large amount of issues, probably including this one as well.

Please see the CONTRIBUTING.md for guidelines on filing issues. You can start from this jsBin template as a starting point and link it in the issue template under "Live Demo".

Feel free to file a new issue following these instructions if you can still reproduce this issue with versions 1 of the polyfills. Thank you!