Remove a value from an array in CoffeeScript

Question

I have an array:

array = [..., "Hello", "World", "Again", ...]

How could I check if "World" is in the array? Then remove it if it exists? And have a reference to "World"?

Sometimes maybe I wanna match a word with a regexp and in that case I won't know the exact string so I need to have a reference to the matched String. But in this case I know for sure it's "World" which makes it simpler.

Thanks for the suggestions. I found a cool way to do it:

http://documentcloud.github.com/underscore

Answer 1

filter() is also an option:

arr = [..., "Hello", "World", "Again", ...]

newArr = arr.filter (word) -> word isnt "World"

Answer 2

array.indexOf("World") will get the index of "World" or -1 if it doesn't exist. array.splice(indexOfWorld, 1) will remove "World" from the array.

Answer 3

For this is such a natural need, I often prototype my arrays with an remove(args...) method.

My suggestion is to write this somewhere:

Array.prototype.remove = (args...) ->
  output = []
  for arg in args
    index = @indexOf arg
    output.push @splice(index, 1) if index isnt -1
  output = output[0] if args.length is 1
  output

And use like this anywhere:

array = [..., "Hello", "World", "Again", ...]
ref = array.remove("World")
alert array # [..., "Hello", "Again",  ...]
alert ref   # "World"

This way you can also remove multiple items at the same time:

array = [..., "Hello", "World", "Again", ...]
ref = array.remove("Hello", "Again")
alert array # [..., "World",  ...]
alert ref   # ["Hello", "Again"]

Answer 4

Checking if "World" is in array:

"World" in array

Removing if exists

array = (x for x in array when x != 'World')

or

array = array.filter (e) -> e != 'World'

Keeping reference (that's the shortest I've found - !.push is always false since .push > 0)

refs = []
array = array.filter (e) -> e != 'World' || !refs.push e

Answer 5

Try this :

filter = ["a", "b", "c", "d", "e", "f", "g"]

#Remove "b" and "d" from the array in one go
filter.splice(index, 1) for index, value of filter when value in ["b", "d"]

Answer 6

A combination of a few answers:

Array::remove = (obj) ->
  @filter (el) -> el isnt obj

Answer 7

_.without() function from the underscorejs library is a good and clean option in case you want to get a new array :

_.without([1, 2, 1, 0, 3, 1, 4], 0, 1)
[2, 3, 4]

Answer 8

CoffeeScript + jQuery: remove one, not all

arrayRemoveItemByValue = (arr,value) ->
  r=$.inArray(value, arr)
  unless r==-1
    arr.splice(r,1)
  # return
  arr

console.log arrayRemoveItemByValue(['2','1','3'],'3')