export const obj = {
    when: function (subordinate /* , ..., subordinateN */) {
        var i = 0,
            resolveValues = core_slice.call(arguments),
            length = resolveValues.length,

            // the count of uncompleted subordinates
            remaining = length !== 1 || (subordinate && jQuery.isFunction(subordinate.promise)) ? length : 0,

            // the master Deferred. If resolveValues consist of only a single Deferred, just use that.
            deferred = remaining === 1 ? subordinate : jQuery.Deferred(),

            // Update function for both resolve and progress values
            updateFunc = function (i, contexts, values) {
                return function (value) {
                    contexts[i] = this;
                    values[i] = arguments.length > 1 ? core_slice.call(arguments) : value;
                    if (values === progressValues) {
                        deferred.notifyWith(contexts, values);
                    } else if (!(--remaining)) {
                        deferred.resolveWith(contexts, values);
                    }
                };
            },

            progressValues, progressContexts, resolveContexts;

        // add listeners to Deferred subordinates; treat others as resolved
        if (length > 1) {
            progressValues = new Array(length);
            progressContexts = new Array(length);
            resolveContexts = new Array(length);
            for (; i < length; i++) {
                if (resolveValues[i] && jQuery.isFunction(resolveValues[i].promise)) {
                    resolveValues[i].promise()
                        .done(updateFunc(i, resolveContexts, resolveValues))
                        .fail(deferred.reject)
                        .progress(updateFunc(i, progressContexts, progressValues));
                } else {
                    --remaining;
                }
            }
        }

        // if we're not waiting on anything, resolve the master
        if (!remaining) {
            deferred.resolveWith(resolveContexts, resolveValues);
        }

        return deferred.promise();
    }
}