On 17 September 2012 19:51, Allen Wirfs-Brock <[email protected]> wrote: > > On Sep 17, 2012, at 12:37 PM, Luke Hoban wrote: >> >> These are good questions. Paul will be attending the TC39 meeting this >> week, and can likely talk to specific details. High level though, we >> statically eliminate the TDZ checks for references to 'let' within the same >> closure body as the declaration. >> > > The other major check that I would expect to be significant, is whether a > inner function that references an outer TDZ binding is (potentially) called > before initialization of the binding. EG: > > { > function f(){return x} > f(); //TDZ check of x in f can not be eliminated > let x=1; > } > > { > function f(){return x} > let x=1; //TDZ check of x in f should be eliminated > f(); > }
Unfortunately, detecting this case in general requires significant static analysis, since f might be called indirectly through other functions (even ignoring the case where f is used in a first-class manner). /Andreas _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
