Subj : Re: ++0 is not a syntax error?
To   : Igor Bukanov
From : Brendan Eich
Date : Wed Aug 18 2004 09:35 am

Igor Bukanov wrote:
> Hi!
> 
> As far as I can see ECMAScript requires that ++0 should produce 
> RuntimeError, not SyntaxError. So, for example, the following should be OK:
> 
> var f = Function('++0')
> 
> and only during call to f RuntimeError should be generated. Microsoft 
> JScript and KDE JavaScript implementation follows this while 
> SpiderMonkey behaves much saner IMO and report SyntaxError during 
> parsing. But does ECMA-267 allow this early error reporting?
> 
> Regards, Igor


Yes, explicitly so, per Section 16 of ECMA-262 Edition 3:

An implementation may treat any instance of the following kinds of 
runtime errors as a syntax error and therefore report it early:

* Improper uses of return, break, and continue.
* Using the eval property other than via a direct call.
* Errors in regular expression literals.
* Attempts to call PutValue on a value that is not a reference (for 
example, executing the assignment statement 3=4).

The last is the one of interest here.

/be

.