react: Upgrading to React v15.2.0 causes my development build to crash IE9

My application crashes IE9 when I upgrade to React v15.2.0! It works fine with v15.1.0 and all earlier versions.

My diff looks like this

package.json
 -    "react-addons-perf": "15.1.0",
 +    "react-addons-perf": "15.2.0",
 -    "react-addons-shallow-compare": "15.1.0",
 +    "react-addons-shallow-compare": "15.2.0",
 -    "react-addons-test-utils": "15.1.0",
 +    "react-addons-test-utils": "15.2.0",
 -    "react": "15.1.0",
 +    "react": "15.2.0",
 -    "react-addons-css-transition-group": "15.1.0",
 +    "react-addons-css-transition-group": "15.2.0",
 -    "react-addons-transition-group": "15.1.0",
 +    "react-addons-transition-group": "15.2.0",
 -    "react-dom": "15.1.0",
 +    "react-dom": "15.2.0",

Below is a GIF of the crash, I recorded this using BrowserStack (Win7, IE9). I start the recording with Google loaded and dev tools open, I then navigated to my apps URL. As you can see IE9 just crashes hard with nothing logged to console. All other browsers load my app just fine, this only seems to crash IE9!

crash

Did you guys drop support for IE9 in 15.2.0? If not, any ideas what might be causing this?

About this issue

Original URL
State: closed
Created 8 years ago
Reactions: 2
Comments: 20 (2 by maintainers)

Commits related to this issue

Refactor `precacheChildNodes` slightly (#8018) This ‘fixes’ a bizarre IE9 script engine issue. #7803 — committed to facebook/react by eoin 8 years ago
Refactor `precacheChildNodes` slightly (#8018) This ‘fixes’ a bizarre IE9 script engine issue. #7803 (cherry picked from commit 6ce8f1f93c1d8758fcaa819ab18c70a7dd65b6aa) — committed to facebook/react by eoin 8 years ago
Refactor `precacheChildNodes` slightly (#8018) This ‘fixes’ a bizarre IE9 script engine issue. #7803 — committed to brandcast/react by eoin 8 years ago

Most upvoted comments

@gaearon thank you for all of your help! I just verified that enabling the UglifyJsPlugin for our development builds does indeed “fix” this issue! @bretthadley thank you for pointing this out!

Funny enough, we already use the UglifyJsPlugin in our production builds so we would not have been blocked by this issue if we were not so good at testing in development 😄

Fear not tho, this experience will not change any of our good testing procedures!

ccoffey on Sep 27, 2016

git bisect indicates that this was introduced in https://github.com/facebook/react/commit/e974383cbace7589501f7c5586c02a9a33124f20.

The change itself isn’t problematic, but it does seem to have triggered an IE9 script engine bug of some sort, resulting in the crash. I’ve found that a small refactor of precacheChildNodes ‘fixes’ the issue, but I’m not entirely sure why. 😞

eoin on Oct 19, 2016