diff_time.js

var hoy = new Date();
var futuro = new Date(2011,02,30);
var diff = futuro-hoy;

diff /= 1000;

var days = Math.floor(diff / (60*60*24) - 27);
diff = diff - (days+27) *(60*60*24);
var hours = Math.floor(diff/(60*60));
diff = diff - hours * (60*60);
var mins = Math.floor( diff / 60 );
var secs = Math.floor(diff - mins * 60);
alert(days+' '+hours+':'+mins+':'+secs);