You could create a Date object, and then build a string from it.
var d = new Date(returnedDate);
var month = d.getMonth() + 1, // month indexed from 0-11
day = d.getDate(),
year = d.getFullYear(), // use instead of getYear() for 4-digit year
hour = d.getHours(),
minute = d.getMinutes(),
second = d.getSeconds();
// Convert to 12-hour time, if that's your thing
if (hour >= 12) {
hour -= 12;
var meridiem = 'AM';
// Correct for midnight
if (hour === 0) hour = 12;
} else {
var meridiem = 'PM';
}
var dStr = month + '/' + day + '/' + year + ' ' +
hour + ':' + minute + ':' + second + ' ' + meridiem;
I'm unfamiliar with C#'s conventions for dates, but that looks pretty close to what you want. Note that this will interpret the time in the local timezone. Normalizing that mostly requires using the UTC methods for the Date object.
Being real here: JavaScript's date libraries are... lacking. I really do recommend using a library for this. I like Moment.js a lot. Read up on parsing a date string and formatting a date for display.