The author is misrepresenting imperative code [0]. Instead of the 42 lines of code he thinks is imperative, but really is already functional-compatible, this is what I would write:

    var getIncompleteTaskSummariesForMember_imperative = function(memberName) {
        return fetchData().then(function(data) {
            var tasks = data.tasks;
            var results = [];
            for (var i = 0; i < tasks.length; i++) {
                var task = tasks[i];
                if (task.member == memberName && !task.complete) {
                    results.push({
                      id: task.id,
                      dueDate: task.dueDate,
                      title: task.title,
                      priority: task.priority
                    })
                }
            }
            results.sort(function(first, second) {
                return first.dueDate - second.dueDate;
            });
            return results;
        });
    }

Still longer than the 10 lines of functional code, but a much more fair comparison.

[0]: http://scott.sauyet.com/Javascript/Talk/2014/01/FuncProgTalk...