IE11 + core-js@3.6.4 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
#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: JakeChampion/fetch#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?

├─ core-js-compat@3.6.4
└─ core-js@3.6.4

[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.