What is this? (function(){ })() [duplicate]

Answer 1

They are the same.

There has to be a parenthesis either around the function definition or around the function call to make it valid Javascript syntax, but it doesn't matter which you use.

To demonstrate what it does, using a named function it would be:

function something() {}

// parenthesis around the function reference:
(something)();

// parenthesis around the function call:
(something());