what does (function () { ... })(); mean?

Question

I see that in many modules for node.js and also for browser, they use to have all their code inside something like this:

(function () {

  moduleName.prototype.variable = 'whatever';

})();

Can anyone please explain what this all is, or any links that explain? I have no idea how to search it! Thanks in advance.

Answer 1

This is a pattern called Immediately Invoked Function Expression.

It's mostly useful for isolation purposes.