What do parentheses surrounding an object/function/class declaration mean? [duplicate]

Answer 1

Juts to follow up on what Andy Hume and others have said:

The '()' surrounding the anonymous function is the 'grouping operator' as defined in section 11.1.6 of the ECMA spec: http://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf.

Taken verbatim from the docs:

11.1.6 The Grouping Operator

The production PrimaryExpression : ( Expression ) is evaluated as follows:

1. Return the result of evaluating Expression. This may be of type Reference.

In this context the function is treated as an expression.