Use of global in ChangeSummary IIFEs breaks loading in node-webkit

[dfreedm]

Moved Polymer/polymer#228 to here.

node-webkit is a project that combines node.js and Chromium, with node.js preloaded into the javascript vm.

node.js uses the global global scope, and starting at Line 1174 in change_summary.js, the use of global will put PathObserver and other modules into the node.js scope and not the window scope.

[richardanaya]

Verified, I was able to fix this just by doing a search replace on "global" to something else

[rafaelw]

I don't know anything about node-webkit. I'm going to close this issue, but ask anyone who this is hurting to submit a PR to fix it.

[wilkerlucio]

I'm having this issue here, it actually starts with not finding ArraySplice... any hint on how to fix that? I really wanna use polymer with node-webkit...

[rafaelw]

The issue here isn't really observe-js, it's all of Polymer. Node's top-level scope isn't the global scope, so the only way to fix this would be to have polymer change to use a node-friendly package system, or to have all uses of symbols check for the symbol in the top-level scope and also on 'global.'

[rafaelw]

@mattsmcnulty

[cadorn]

change to use a node-friendly package system, or to have all uses of symbols check for the symbol in the top-level scope and also on 'global.'

I would not single out NodeJS here. NodeJS is not the only server environment and I can see polymer being used on others.

Check for exports global to detect CommonJS environment as a start.

[wilkerlucio]

agreed with @cadorn

[wilkerlucio]

actually I found a fix here, I got the compiled polymer file, search and replace "global" with something else (I used fakeGlobal, but almost any name will do the same). but it's hacky and ugly...

[FunkMonkey]

The problem is the last line of observe.js, which tries to differentiate between node.js and the browser:

})(typeof global !== 'undefined' && global ? global : this || window);

In a node-webkit html page, both global and window exist. Unfortunately observe is polyfilled on global though it is needed on window. But as @cadorn pointed out, exports does not exist in a node-webkit html page, neither does module. And this points to window and not to exports as in a node.js module.

There are various ways to check for node-webkit now, one of them could simply be:

})(typeof global !== 'undefined' && global && typeof module !== 'undefined' && module ? global : this || window);

@rafaelw: As I see it, this issue is not effecting all of polymer, but only the javascript-specific polyfills like Object.observe which are designed to work in node.js too. All browser polyfills don't work in node anyway... Thus WeakMap should be the only other that might need such a fix, but looking at the source, it is currently browser-only anyway (relying on window)