I had to make a minor change to it though. Sunday is the first day of the week in the US, so I had to update the days array in the code:

daysLong: ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"],
daysShort: ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"],

Thanks!

Here what are you doing is comparing apples and pears. JavaScript is a language and .NET is an runtime environment. Which is on top of that also: language agnostic.

Comparing JavaScript to C# might have much more sense.
But it seems to me, the most sensible approach would be not to mention .NET or C# at all and just present the solution.

There is a simple but very useful general format() which is also ".net like" if that is a mark of the quality:

//
// .net string.format like function
// usage: "{0} means 'zero'".format("nula")
// returns: "nula means 'zero'"
// place holders must be in a range 0-99.
// if no argument given for the placeholder,
// no replacement will be done, so
// "oops {99}".format("!")
// returns the input
// same placeholders will be all replaced
// with the same argument :
// "oops {0}{0}".format("!","?")
// returns "oops !!"
//
if ('function' != typeof String.format)
String.prototype.format = function() {
var args = arguments;
return this.replace(/\{(\d|\d\d)\}/g, function($0) {
var idx = 1 * $0.match(/\d+/)[0]; return args[idx] !== undefined ? args[idx] : (args[idx] === "" ? "" : $0);
}
);
}

Thanks …

Good Luck!