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thomasboyt/reverse.js

Created August 18, 2016 01:32
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why is js's implementation of reverse() so awful
Raw
reverse.js
> var a = [1,2,3]
undefined
> a.reverse()
[ 3, 2, 1 ]
> a
[ 3, 2, 1 ]
// [insert price is right losing horn here]
Raw
reverse.py
>>> arr = [1, 2, 3]
>>> ret = arr.reverse() # mutates arr
>>> print ret
None
>>> arr
[3, 2, 1]
>>> arr = [1, 2, 3]
>>> reversed(arr) # does not mutate arr
<listreverseiterator object at 0x101763610>
>>> [x for x in reversed(arr)]
[3, 2, 1]
>>> arr
[1, 2, 3]
Raw
reverse.rb
irb(main):001:0> a = [1,2,3]
=> [1, 2, 3]
irb(main):002:0> a.reverse
=> [3, 2, 1]
irb(main):003:0> a
=> [1, 2, 3]
irb(main):004:0> a.reverse!
=> [3, 2, 1]
irb(main):005:0> a
=> [3, 2, 1]
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