Why embed the JavaScript class in an anonymous function() call?

Question

I was reading about the new JavaScript-like language from Microsoft called TypeScript. In the playground (example section), there is a simple class in TypeScript syntax converte

Answer 1

The following is called an Immediately Invoked Function Expression:

(function(){ ... })();

It is used to keep the global scope clean. Though, in this case it isn't necessary since the return value is assigned to a variable Greeter. The only time this pattern is useful is when you want "private" static members.

E.g.:

var Greeter = (function () {
    var foo = 'foo', bar = 'bar'; /* only accessible from function's defined
                                     in the local scope ... */

    function Greeter(message) {
        this.greeting = message;
    }
    Greeter.prototype.greet = function () {
        return "Hello, " + this.greeting;
    };
    return Greeter;
})();