Reset/Undo in Knockout.js

resettable.coffee

    ko.extenders.resettable = (target, option) ->
        if option
            original = ko.utils.unwrapObservable(option.initialValue) ? ''
            if $.isArray(original)
                copiedOriginal = $.extend(true, [], original)
            else if typeof original is 'object'
                copiedOriginal = $.extend(true, {}, original)
            else
                copiedOriginal = original


        target.reset = ->
            if copiedOriginal
                if $.isArray(copiedOriginal)
                    target.removeAll()
                    $.each(copiedOriginal, (index, value) -> target.push(value) )
                else
                    target(copiedOriginal)
        return target;