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Collections are a way for you to organize kata so that you can create your own training routines. Every collection you create is public and automatically sharable with other warriors. After you have added a few kata to a collection you and others can train on the kata contained within the collection.
Get started now by creating a new collection.
That's the point of this kata (at least for JS version): extend array functionality with a new method. It doesn't exist, but you can write your own functions that extend a prototype (Array).
I don't understand the point of your question.
Do you know the whole JS documentation is available online? If I type
js re
into Google, the autocompletion immediately proposes meje remove element from array
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