change calendar type based on device screen size

Try this

var smallscreen = (window.screen.width < 800);

if (smallscreen) {
    // use a weekly or daily calendar
    var dp = new DayPilot.Calendar("calendar", {
        //viewType: "Week",
        timeRangeSelectedHandling: "Disabled",
        eventMoveHandling: "Disabled",
        eventResizeHandling: "Disabled",
        eventDeleteHandling: "Disabled",
        eventClickHandling: "Enabled",
        eventRightClickHandling: "Disabled",
    });

    DayPilot.Locale.weekStarts = 1;
    dp.locale = 'en-gb';
    dp.theme = "month_transparent";
    dp.startDate = DayPilot.Date.today();

} else {
    var dp = new DayPilot.Month("calendar", {
        timeRangeSelectedHandling: "Disabled",
        eventMoveHandling: "Disabled",
        eventResizeHandling: "Disabled",
        eventDeleteHandling: "Disabled",
        eventClickHandling: "Enabled",
        eventRightClickHandling: "Disabled",
    });

    DayPilot.Locale.weekStarts = 1;
    dp.locale = 'en-gb';
    dp.theme = "month_transparent";
    dp.startDate = DayPilot.Date.today();
}

Cheers
Ted

Great, thanks for posting your solution!