In JavaScript you can extend the available methods of built-in objects like Strings and do stuff like this:

String.prototype.trim = function(){return this.replace(/^\s+|\s+$/, '');};

Which then allows you to do this:

alert(document.forms[0].SomeField.value.trim());

Which I always prefer to the alternative which would look something like this:

alert(trim(document.forms[0].SomeField.value));

Dunno why. I just think it looks more professional. There are probably good reasons to do it this way as well. Say, like, it stops you accidentally making two trim methods which do two different things.

Until today I'd never realised you can do this in "real" programming languages too. Well, at least you can in C#.

Here's a string extension helper method to encrypt a password:

public static class StringExtensions
{
 public static string Encrypt(this string password)
 {
  return BitConverter.ToString(
        SHA1Managed.Create().ComputeHash(
                Encoding.Default.GetBytes(password)
        )).Replace("-", "");
 }
}

The key here is that the class and method are both static and also that we're using the "this" keyword before the string argument we're passing to the method. This tells C# the argument can be passed to it by calling our new method on a string. Like so:

Console.WriteLine("my password".Encrypt());
Console.WriteLine(Request["MyPassword"].Encrypt());

Nice.

I'm now in the process of retro-fitting this approach to a couple of apps I've done recently.

It follows that you can do the same thing for other objects, such as DateTime. Here's a helper method to turn a date in to words -- such as "Three weeks ago":

public static class DateExtensions {
 public static string ToWords(this DateTime dateTime)
 {
   //Code to do this for real is on Google et al
   return "Three weeks ago";
 }
}

The beauty of doing this in C# is that Visual Studio's Intelli-sense picks up on these new extensions and adds them to type-ahead, as you can see below in this Razor-based MVC View:

Working with C# and Visual Studio really is a pleasure. It makes learning to be a real programmer after all these years so much easier.