I don't think that can be done RELIABLY with built in methods on the native Date object. The toLocaleString method gets close, but if I am remembering correctly, it won't work correctly in IE < 10. If you are able to use a library for this task, MomentJS is a really amazing library; and it makes working with dates and times easy. Otherwise, I think you will have to write a basic function to give you the format that you are after.
function formatDate(date) {
var year = date.getFullYear(),
month = date.getMonth() + 1, // months are zero indexed
day = date.getDate(),
hour = date.getHours(),
minute = date.getMinutes(),
second = date.getSeconds(),
hourFormatted = hour % 12 || 12, // hour returned in 24 hour format
minuteFormatted = minute < 10 ? "0" + minute : minute,
morning = hour < 12 ? "am" : "pm";
return month + "/" + day + "/" + year + " " + hourFormatted + ":" +
minuteFormatted + morning;
}