Fluentui: Website not loading in IE11

[mikewheaton]

Bug Report

• __Package version(s)__: Latest
• __Browser and OS versions__: Windows IE 11

Priorities and help requested:

Are you willing to submit a PR to fix? Yes

Requested priority: Blocking

Products/sites affected: Fabric website

Describe the issue:

The Fabric website is not loading in IE 11 because we're using object.assign somewhere. Here is the console error:

Object doesn't support property or method 'assign'

I recall this coming up before and thought it was fixed, but haven't been able to find an issue for that to re-open. It's also possible that this was fixed and just hasn't been deployed yet.

Actual behavior:

The website doesn't load.

Expected behavior:

The website loads.

[cliffkoh]

@mikewheaton FYI Rank is for features, Priority is for bugs :)

[cliffkoh]

On my machine, it looks like the error comes from tslib but that should not be the cause.. Otherwise, peoplepicker.types,example is the only direct object.assign usage but that has been there for over a year...

[cliffkoh]

Hey @mikewheaton @Jahnp , the website is super duper old (over 2 months). Looking at the existing code, this should not happen. In fact, the local copy works fine with IE 11.

Did you know if we roll backed to 6.49.2 recently? I think we hit this problem before and @JasonGore had deployed a fix before..

[Jahnp]

Hey @cliffkoh , we rolled back during the last week of September since the site infra had not yet been updated to use React 16.3, which caused the site to not render in any browser. Those updates went through on Monday, and we're in the process of actually updating the site to use the new pipeline. I'd expect it to be updated within the next few hours; I'll revisit this issue then.

[Jahnp]

This was also brought up in #6668 , which we closed due to imminent updates that took a little longer than expected. I'm going to keep this open until I've verified the latest is published.

[mikewheaton]

The site has been updated and I've verified that it's loading in IE11. Thanks, @Jahnp!