I found such two code and not understand the difference between them if any exists.
Can you explain me what is difference between code preventing global scope polution.
First:
(function() {
var x = 1;
// thousand of lines here
}(window));
Second:
(function() {
var x = 1;
// thousand of lines here
})(window);
Question can be trivial but I am not understand difference what is doing (); - can you explain it?
When the JavaScript parser reads a function token at the start of the line, it assumes it’s a function declaration, i.e.
function hello() {
return "world";
}
When it doesn’t see a name after that, it’s a syntax error. The parentheses make the context an expression instead of a statement/declaration, meaning that a function literal is expected.
Fun fact: you don’t need parentheses to force an expression context, of course. Unary operators will work too, e.g.
!function() {
var x = 1;
}();
Oh, and you’ve gone and changed the question. The new answer is: they’re both exactly the same, kind of like 5 + (4 * 3) versus (5 + 4 * 3), except even less important because they’re more or less equally readable.
