“The self invoking function pattern does get misused by people who don’t really understand what it does”

I know “what it does”, but I’m the first to say that I misuse it quite a lot.

Also, it’s quite difficult to know what classes as “misuse”. Say, for example, I have to prepare a value – this only needs to happen once – but the preparation of this value is complex, and would certainly complicate the surrounding code if left un-contained. In such a situation I would use the mentioned construct to provide such containment.

@Nick, what sucks is that the with statement has been deprecated in ES5. It’s a classic case of punishing the whole class because a couple kids mess around. Sure, the with statement can be misused, but it can also be used to great effect.

I believe that Andrea’s point was not that self invoking functions are inherently “bad”, but that they have their use cases. Many people (myself included) have used or do use self invoking functions to avoid polluting whichever namespace they are inside (which is great when in the global scope, as you and many others will point out). Often times, you can achieve the same thing with less code, and without creating an unnecessary closure by using the with statement.

If I were to boil it down to the essence (apologies to Andrea if I butcher anything): Every trick can be used or misused (self invoking functions and with), but that doesn’t mean we should blindly refuse to use one or the other, but that we should think about which will be best for the current situation.

The self invoking function pattern does get misused by people who don’t really understand what it does, but it is popular for a good reason; @nick the example may be out of context but if it was standalone then it would prevent a global variable, which is a real benefit.

Having looked at the Andrea Giammarchi example use of ‘with’ I notice it has a very dubious reliance on the implied end-of-line semi-colon, I’d run a mile from that

// avoid global scope pollution
(function(e){
  e.insertBefore(
    document.createElement("script"),
    e.firstChild
  ).text = "alert(1)"
  ;
   // feeling cool and clever
   // just to avoid "var"
})(document.documentElement);

http://webreflection.blogspot.com/2009/12/with-worlds-most-misunderstood.html

I have to admit that I am guilty of doing exactly this. I think JS just needs a “let” expression similar to Lisp’s (very different from the JS 1.8 “let” statement).

I often do the self invoking function thing on returns when I can’t squeeze a “return foo ? bar : baz;” in there instead. I think in those cases it is acceptable (though I have definitely misused self invoking functions plenty).

I’ll be honest though, I don’t think I’ve EVER been so lazy I couldn’t type out a proper Array!