There are three ways to define a function in Javascript; the third is exemplified in the example above, although it's not usually done with the same name for the variable and for the function.
The value of naming a function as you assign it to a variable is that, when an exception arises within the function body, your error log output contains the function name, which doesn't always happen when you simply do "var foo = function () {...}". (It's also handy when you're using an editor which doesn't understand Javascript well enough to understand that "var foo = function () {...}" actually creates a function named "foo"; in such cases, explicitly naming the function clues in the editor's parser, which simplifies code navigation.)
The value of naming a function as you assign it to a variable is that, when an exception arises within the function body, your error log output contains the function name, which doesn't always happen when you simply do "var foo = function () {...}". (It's also handy when you're using an editor which doesn't understand Javascript well enough to understand that "var foo = function () {...}" actually creates a function named "foo"; in such cases, explicitly naming the function clues in the editor's parser, which simplifies code navigation.)