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Discussion on: 5 JavaScript "tips" that might bite you back.

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Replies for: Note that your ordering is a bit weird. You could do this (swap b and a in the reduce): function union(...arrays) { return arrays.reduce((resu...

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thepeoplesbourgeois profile image
Josh •

Every single time I use reduce, I forget how whichever language I'm using it in organizes either its own arguments, or the arguments given to its lambda/block. 🤦‍♂️

Ruby:

init = 0
(1..10).reduce(init) do |accumulator, iteration| 
  accumulator + iteration  
end # 55
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Elixir:

init = 0
Enum.reduce(1..10, init, fn iteration, accumulator ->
  accumulator + iteration
end) # 55
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And now, (thank you,) Javascript:

function union(a, ...b) {
  return b.reduce((accumulator, iteration) => [...accumulator, ...iteration], a)
}
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eecolor profile image
EECOLOR •

Haha, yeah. In Scala you have foldLeft and foldRight, where foldLeft has it as the first argument and foldRight as the second argument.