Попробуйте это:
var myDate = new Date("2010-09-21T15:48:12.754+02:00")
alert(myDate);
EDIT
Если вы хотите, вы можете написать свой собственный формат даты, например:
var date = new Date("2010-09-21T15:48:12.754+02:00");
var days = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat'];
var months = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'];
var myDate = '';
myDate += days[date.getDay()] + " " + months[date.getMonth()] + " " + date.getDate() + " ";
myDate += date.getHours() + ":" + date.getMinutes() + ":" + date.getSeconds() + " ";
myDate += "0" + date.getTimezoneOffset() / 60 + ":00 " + date.getFullYear();
alert(myDate);
См. В jsfiddle .
EDIT
Другой пример:
// crazy date
var date = new Date("2010-09-22");
var days = ['Weekend!', 'Workday', 'Workday', 'Workday', 'Workday', 'Workday', 'Weekend!'];
var months = ['Winter', 'Winter', 'Spring', 'Spring', 'Spring', 'Summer', 'Summer', 'Summer', 'Autumn', 'Autumn', 'Autumn', 'Winter'];
var myDate = "We are in " + months[date.getMonth()] + " and today is a " + days[date.getDay()];
alert(myDate);