The second parameter is an anonymous function. [unanamed funciton]
It could be a named one too.
JavaScript looks at the 2nd parameter and says what do I have here? I have a
string, I will just insert that in. In our case it says I have a function. I will pass in whatever I matched to it as an argument and will use whatever it returns back and use that.
JavaScript is powerful when you learn about these things!
Eric