I have this recursive function that searches an object tree structure:

dataSearcher = (dataElement, identifierToFind) -> 
    if dataElement.identifier == identifierToFind
        return dataElement
        for childDataElement in dataElement.children
            found = dataSearcher childDataElement, identifierToFind
            if found then return found

Which I then call thus:

foundDataElement = dataSearcher @options.nodeData, identifier

It works just fine so I am happy about that, but I am pretty new to CoffeeScript and would like feedback on the way I structured it. The loop I used seems a bit old school, so could I have used a comprehension here instead? Any other feedback would be great as I am still getting my head into the CoffeeScript idiom.

Please let me know if I should edit with more context code.

  • 2
    \$\begingroup\$ You could make the for a comprehension, but it wouldn't cut the visit short when a match was found, so while this is less "functional" it's just as good. The real test of code is this: which do you expect to be able to read six months from now? I'd remove the 'else', but that's my Haskell training talking: you've got a guard condition at the top of your function, not an alternative, but that's how I read things. \$\endgroup\$ – Elf Sternberg Jan 6 '12 at 18:34
  • 1
    \$\begingroup\$ side note: the functional abstraction for what you are doing is mapDetect (see gist.github.com/1222480 for a underscore implementation). In a lazy language it would be (head . filter predicate). \$\endgroup\$ – tokland Jan 7 '12 at 14:42

I'd prefer writing it like this:

dataSearcher = (element, identifier) -> 
  return element if element.identifier is identifier
  for child in element.children
    found = dataSearcher child, identifier
    return found if found


  • guard style instead of else (one less level of indentation)
  • postfix if (probably a question of style)
  • is instead of ==
  • shorter variable names
  • \$\begingroup\$ That is the sort of thing I am looking for...I am pretty clear I am still writing my coffeescript in a js idiom. Good coaching. \$\endgroup\$ – Matthew Nichols Jan 6 '12 at 23:29

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