Code for "Determining if a device is a tablet on Titanium Appcelerator" blog post: http://www.libtronics.com/2013/10/determining-if-device-is-tablet-on.html

isTablet.js

var osname = Ti.Platform.osname;
var version = Ti.Platform.version;
var dpi = Ti.Platform.displayCaps.dpi;
var height = Ti.Platform.displayCaps.platformHeight;
var width = Ti.Platform.displayCaps.platformWidth;
if (height < width){
	var w_inch = height /  Ti.Platform.displayCaps.xdpi;
	var h_inch = width /  Ti.Platform.displayCaps.ydpi;
}else{
	var w_inch = width /  Ti.Platform.displayCaps.xdpi;
	var h_inch = height /  Ti.Platform.displayCaps.ydpi;
}
var disp_size = Math.sqrt(w_inch*w_inch+h_inch*h_inch);
var is7inch = (disp_size > 6.99)? true: false;

//Ti.API.info('Width: '+width+', Height: '+height+', size: '+disp_size);
//Ti.API.info('w_inch: '+w_inch+', h_inch: '+h_inch);

var isTablet = osname === 'ipad' || (osname === 'android' && is7inch);