JS function closure

greeter.js

function greeter(saluatation) {
    var counter = 0;                      // If in java counter needs to be defined as final
    var prefix = '. ' + saluatation + ' ';
    return function (name) {              // is bound to counter and prefix, (we call the variables that we are bound to closure)
        counter++;                        // same reference to the outter counter, therefore keeps state
        return counter + prefix + name + '!';
    };
}

var greet = greeter('Hello');
greet('World');   // 1. Hello World!
greet('World');   // 2. Hello World!