Popper.js with Bootstrap

popper.js v2.0 not compatible with bootstrap v4. Use v1.0 instead.

https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js

https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js.map

Popper.js official

https://popper.js.org/

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