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@babel/polyfill loaded multiple times #2955

klaemo opened this Issue Dec 14, 2018 · 2 comments


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klaemo commented Dec 14, 2018


Knex version: 0.16.2
Database + version: Postgres 9 + CockroachDB
OS: macOS + linux


@babel/polyfill is loaded more than once on this page. This is probably not desirable/intended and may have consequences if different versions of the polyfills are applied sequentially. If you do need to load the polyfill more than once, use @babel/polyfill/noConflict instead to bypass the warning.

This might happen because we require knex in two different files as we use two different databases. If knex is only to be required once per server/app (which would be weird), I guess that should be mentioned somewhere? Did I miss that?

I think it's not a good practice to include @babel/polyfill in a library. Like in the browser libraries shouldn't mess with the global scope. From the @babel/polyfill documentation:

This will emulate a full ES2015+ environment (no < Stage 4 proposals) and is intended to be used in an application rather than a library/tool.


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kibertoad commented Dec 19, 2018

0.16.3 is out with a fix for this.


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klaemo commented Dec 23, 2018

Thank you!

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