Why is this function wrapped in parentheses, followed by parentheses? [duplicate]

Answer 1

I'm not sure if this question is answered already, so apologies if I'm just repeating stuff.

In JavaScript, only functions introduce new scope. By wrapping your code in an immediate function, all variables you define exist only in this or lower scope, but not in global scope.

So this is a good way to not pollute the global scope.

There should be only a few global variables. Remember that every global is a property of the window object, which already has a lot of properties by default. Introducing a new scope also avoids collisions with default properties of the window object.