in realtà ho risolto così...


var temp1 = data1.split(/[/]/);
var temp2 = data2.split(/[/]/);

var dataF = new Date(temp1[2], parseInt(temp1[1],10) -1, temp1[0]);
var dataC = new Date(temp2[2], parseInt(temp2[1],10) -1, temp2[0]);

diff = (dataF - dataC) / (1000 * 3600 * 24) ;