Chrome seems to have issues with Meteor when its Data Saver feature is used on HTTP

[greggman]

My site www.vertexshaderart.com wasn't working on Chrome on iOS. I narrowed it down to their Data Saver feature. Turning it off fix the issue.

I'm sure the chrome team would like it to just work so I filed a bug.

In the meantime I'm trying to see if can add the header they mentioned to work around the issue. They say adding Cache-Control: no-transform should disable the data saver feature.

At the moment I have that being served by most requests but it's not enough. Missing is adding that to sockjs and websocket responses. I'm in the process of just hacking that in to see if it solves the issue.

[greggman]

So I think this patch to sockjs works around the issue. I hacked it into my site and it started working.

[zol]

Hey @greggman . Thanks for reporting this. Does this issue break your site in a major way? (that your patch works around?)

[greggman]

Yes, the site doesn't work at all because of this issue. DDP never gets started.

Google looked into the issue. The specific issue is SocksJS is marking a couple of XHRs it does at the beginning as JSON but they aren't actually JSON. Google's Data Saver feature (and other proxies possibly as well) uses content aware compression. So, they see the content is marked as "JSON" and they remove any insigifinicant whitespace. SocksJS is incorrectly looking for that insignificant whitespace since they're claiming it's JSON they shouldn't be looking at whitespace.

There's 3 workarounds.

• SocksJS should stop looking for insiginicant whitespace

or

• SocksJS should stop marking the XHR as JSON if it's not actually JSON

or

• Set the no-transform header and hope that all proxies respect it.

[geeksville]

Thanks @greggman - I too had users reporting this problem (my site was dead on Android if the user had turned on data saver). Your patch fixed it for me.

[abernix]

Thanks for reporting this issue originally, @greggman. Sorry this didn't get followed up on sooner!

I've just dug through a bit and see the Chromium team filed an issue with SockJS (sockjs/sockjs-node#190) and (your) PR was merged into sockjs@0.3.16. Meteor has been using sockjs@0.3.17 since Meteor 1.3.3 (233b24e) so this is fixed in recent versions of Meteor!

Great find and fix on this. Closing as resolved. :)