Problem

You have an array in CoffeeScript, which contains equal elements multiple times such as:

[1,1,2,3,3]

You would like to have only unique values in the array. Thus, transform it into:

[1,2,3]

Solution

You can use the following method to accomplish such:

removeDuplicates = (ar) ->
  if ar.length == 0
    return []  
  res = {}
  res[ar[key]] = ar[key] for key in [0..ar.length-1]
  value for key, value of res

alert(removeDuplicates([1,2,3,3,4,4,5]));

References

This solution is based on this approach (with a few minor issues fixed).