Moving Raphaël elements up and down the stack, one by one

shift.coffee

shift = (element, dir) ->
    if dir is "down"
        fn   = "insertBefore"
        prop = "prev"
    else
        fn   = "insertAfter"
        prop = "next"

    # sibling (either next or previous)
    sib = element[prop]
    
    # you might also want to check the type of `sib` here
    while sib then sib = sib[prop]

    # call `insertBefore/After` on element in relation to
    # its sibling
    if sib then element[fn] sib

# usage:
shift myElement, "up"
shift myElement, "down"