On Wed, Feb 16, 2011 at 8:33 PM, Dmitry A. Soshnikov
<[email protected]> wrote:
> Hey Diego,
>
> Yes, that's of course correct (but it seems was easy for to answer, that's
> why I wanted that OP answered ;). Anyway, yes, your answer is completely
> correct and as I mentioned at the beginning it's related with ASI.
>
It was easy because I walked over it in the past not because it made
sense at the time :)
Though I have learned that it is necessary for the parser to have this
disambiguated first, thus ASI.
--
Diego
> (Another change which will avoid the syntax error is to return a function
> from the "foo" in version 1. Though, being syntactically correct such a
> program obviously semantically and logically is buggy).
>
> Dmitry.
>
> On 16.02.2011 16:47, Diego Perini wrote:
>>
>> Dmitry,
>> if you correctly insert the missing semicolons both versions work,
>> without semicolons both version fail.
>>
>> Version 1:
>>
>> var foo = function () {
>> return "foo";
>> };
>>
>> (function () {
>> return "IIFE";
>> })();
>>
>> Version 2:
>>
>> var foo = function () {
>> return "foo";
>> };
>>
>> (function () {
>> return "IIFE";
>> }());
>>
>> Try them in a console, the correct result is when the "IIFE" string is
>> printed out.
>>
>> Without semicolon, "Version 2" will not throw errors but will not
>> produces the "IIFE" string either.
>>
>> The problem is that in "Version2" the "IIFE" string just become a
>> parameter to the self invoking function resulting by omitting the
>> semicolons.
>>
>> var foo = function () { return "foo"; }(function () { return "IIFE"; }());
>> var foo = function () { return "foo"; }("IIFE");
>>
>> ASI is hard.
>>
>> --
>> Diego
>>
>>
>> On Wed, Feb 16, 2011 at 12:26 PM, Dmitry A. Soshnikov
>> <[email protected]> wrote:
>>>
>>> The only observable difference is a very specific. It related with ASI
>>> (automatic semicolon insertion) mechanism. E.g.
>>>
>>> Version 1:
>>>
>>> var foo = function () {
>>> return "foo";
>>> }
>>>
>>> (function () {
>>> return "IIFE";
>>> })();
>>>
>>> Version 2:
>>>
>>> var foo = function () {
>>> return "foo";
>>> }
>>>
>>> (function () {
>>> return "IIFE";
>>> }());
>>>
>>> The version 1 fails, the second one -- does not. Why? Which changes to
>>> provide for that version 1 don't fail?
>>>
>>> But as mentioned, this case is very specific and just academical. In real
>>> practice, only the convenience in this case does matter.
>>>
>>> (function () {})(); -- here first we get a FE (evaluating the expression
>>> inside the grouping operator) and the call it.
>>>
>>> (function () {}()); -- here we evaluate the grouping operator which
>>> directly
>>> evaluates the function execution.
>>>
>>> Additional info:
>>>
>>> http://dmitrysoshnikov.com/ecmascript/chapter-5-functions/#question-about-surrounding-parentheses
>>>
>>> Dmitry.
>>>
>>>
>>> On 15.02.2011 11:53, Ivan S wrote:
>>>>
>>>> Hi all.
>>>>
>>>> I don't know ECMA script specification so well, so if someone can
>>>> explain
>>>> what's the difference between this two:
>>>>
>>>>
>>>> (function() {
>>>>
>>>> }());
>>>>
>>>>
>>>> (function() {
>>>>
>>>> })();
>>>>
>>>>
>>>> (brackets have different positioning)
>>>>
>>>>
>>>> Intuitively, I can understand the difference, but I would like technical
>>>> explanation.
>>>>
>>>>
>>>> Thank you very much.
>>>>
>>>>
>>>>
>>>> Ivan
>>>> --
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>>>
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>
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