Not In Array- is now possible

Using a custom DMX Formatter would be the best solution right now. Although this would make for a good addition I suppose.

You will have to create a formatter, say whereNotInArray, and use JS to filter and return the list.

dmx.Formatter('array', 'whereNotInArray', function (val, propertyName, arrayValues) {

    if (arrayValues == null || arrayValues.length == 0)
        return null;

    if (propertyName == null)
        throw Error("Incorrect parameters.");

    var returnVal = [];
    
    for (var i = 0; i < val.length; i += 1) {
        var isInArray = false;

        for (var j = 0; j < arrayValues.length; j += 1) {
            if (val[i][propertyName] == arrayValues[j]) {
                isInArray = true;
                break;
            }
        }

        if (!isInArray)
            returnVal.push(val[i]);
    }

    return returnVal;
});

Call it like so:

getProgList.data.getProgs.whereNotInArray('programme_id', arrProgrammesSelected.items)

Haven't tested the JS. So please debug if any issues. Run this script after page load has completed.

More on client-side & server-side custom formatters/modules: