Core-js: IE11 + [email protected] String.prototype.split doesn't work with regexp

[kmsheng]

repo to reproduce
https://github.com/kmsheng/core-js-bug

Note that core-js was imported twice,
one in src/js/index.js and the other one in assets/js/default.js

simlar issue
https://github.com/zloirock/core-js/issues/741

[jaynetics]

i encountered the same bug, and can confirm that importing core-js into two js files is the root cause. importing it in only one file fixes the problem.

[11101101]

I'm also running into the same issue. My code path results in a second import which causes the bug to manifest.

[pierremanceaux]

In case this helps someone: https://github.com/github/fetch/issues/748
It would be great to identify which version of IE11 is/are affected, but it seems pretty recent to me, probably the last build.

[aliaksandr-yermalayeu]

Hi everyone. I am facing the same issue. It is still reproduced in IE11 with the latest version of core-js. However the scenario is pretty tricky to reproduce. So I created a minimal repo with needed steps. Hope it helps.

[sargismarkosyan]

Hi, the issue is reproducible with other regexp too for example '/test/'.split(/\W/) is returning ["/", "t", "e", "s", "t", "/"] but should return ["", "test", ""].

[slowcheetah]

Please show your npm list | grep core-js

[aliaksandr-yermalayeu]

@slowcheetah, will result of yarn list --pattern core-js work for you?

├─ [email protected]
└─ [email protected]

[aliaksandr-yermalayeu]

I took a deeper dive into this issue. The problem is caused by this line. It turns out regexp.exec and regexpExec are different references when polyfill is loaded twice.

[steveworkman]

Is there an older version of core-js that does not show this issue? It looks like there were changes related to adding more regexp.exec requires in 3.6.2
Would a downgrade to 3.6.1 work?

[jdreesen]

I downgraded to 3.5.0 yesterday and it works for me.

[aliaksandr-yermalayeu]

The bug was introduced by version 3.6.0 due to support of y flag. In version 3.5.0 exec was never patched in IE.

[toxik]

is reverting the sticky flag support considered?

[slowcheetah]

@toxik Not yet. But I think about it, because I can’t make it work correctly and break nothing

[toxik]

@slowcheetah have you got any news regarding a revert/fix ? thanks

[toxik]

you can upgrade XRegExp to v4.4.0 instead – https://github.com/slevithan/xregexp/issues/300

[scrollbar-ww]

same problem with 3.8.0.
I put a .replace() before call String.split() as a short term fix :
str.replace(someRegexp/g, ' \n').split('\n')