If you didn't have any control over how the data is structured and were stuck with the 2 arrays (which were dense and had the same length), then using ECMA5 methods you could sort them like this.
Javascript
var dates = [
new Date(2014, 4, 11, 10, 10, 0).getTime(),
new Date(2012, 4, 10, 8, 20, 0).getTime(),
new Date(2013, 4, 9, 7, 20, 0).getTime(),
new Date(2010, 4, 7, 12, 59, 0).getTime()
],
newsItems = ["NewsItem1", "NewsItem2", "NewsItem3", "NewsItem4"];
dates.map((function (date, index) {
return {
date: date,
item: this[index]
};
}), newsItems).sort(function (a, b) {
return b.date - a.date;
}).forEach(function (record, index) {
dates[index] = record.date;
newsItems[index] = record.item
});
console.log(dates, newsItems);
Output
[1399795800000, 1368076800000, 1336630800000, 1273229940000] ["NewsItem1", "NewsItem3", "NewsItem2", "NewsItem4"]
On jsFiddle