How do I write an extension method in JavaScript?
<p>I need to write a few extension methods in JS.  I know just how to do this in C#.  Example:</p>

<pre><code>public static string SayHi(this Object name)
{
    return "Hi " + name + "!";
}
</code></pre>

<p>and then called by:</p>

<pre><code>string firstName = "Bob";
string hi = firstName.SayHi();
</code></pre>

<p>How would I do something like this in JavaScript?</p>
