[Issue] Remove `Array.from` polyfill from PrototypeJS 1.7.3 included in `legacy-build.min.js`

[m2-assistant[bot]]

This issue is automatically created based on existing pull request: magento/magento2#38911: Remove Array.from polyfill from PrototypeJS 1.7.3 included in legacy-build.min.js

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PrototypeJS v1.7.3 included in legacy-build.min.js breaks native Array.from by forcing its own polyfill implementation effectively breaking 3rd party code run on Magento frontend. I

Steps to reproduce

• on Magento frontend run Array.from(new Set([1, 2, 3])) snippet
• observe output [] empty array

Expected output

• array with 3 elements [1, 2, 3]

Description (*)

Commenting out Array.from=$A; from legacy-build.min.js

Related Pull Requests

Fixed Issues (if relevant)

1. Fixes magento/magento2#

Manual testing scenarios (*)

Steps to reproduce

• on Magento frontend run Array.from(new Set([1, 2, 3])) snippet
• observe output [] empty array

Expected output

• array with 3 elements [1, 2, 3]

Questions or comments

Contribution checklist (*)

• [ ] Pull request has a meaningful description of its purpose
• [ ] All commits are accompanied by meaningful commit messages
• [ ] All new or changed code is covered with unit/integration tests (if applicable)
• [ ] README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• [ ] All automated tests passed successfully (all builds are green)

[m2-assistant[bot]]

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[engcom-November]

Hello @stefanbackor,

Thank you for the report and collaboration!

We are not able to reproduce this on 2.4-develop. With PrototypeJS 1.7.3 we got the expected result:

Please let us know if we are missing something.

Thank you.

[stefanbackor]

@engcom-November legacy-build.min.js has to be loaded since this is the script which delivers PrototypeJS. Default theme (installation) does not load such file into storefront. Could legacy-build.min.js be theme dependent?

Searching thru codebase reveals few hacks in regards of Array.from and uppy library.

Testing on Admin Backend does have this issue present.