string1:
string2:



This example demonstrates a very powerful aspect of making your code re-useable!!!!
Note that concatenateTwoStrings(str1,str2) doesn't care about the source of the strings, it only knows that if you 'pass in' two strings it can concatenate and alert them to the user.

Side note, this would be a good example of how JavaScript is loosely-typed, because if you pass in number values for str1 and str2 you might be slightly surprised by the result.