you might consider ticketing performance bugs against the various implementations.
Allen On Jul 10, 2013, at 9:16 AM, Claus Reinke wrote: > The TypeScript project tries to emulate arrow functions through the > "_this = this" pattern and keeps running into corner cases where a > semi-naïve renaming is not sufficient. > > I have been trying to suggest using .bind to emulate arrow functions > instead, but the counter-arguments are (a) .bind might not be available > (supporting pre-ES5 targets) and (b) .bind is slow. > > The polyfill isn't the problem, but I'm a bit shocked every time > someone reminds me of the performance hit for using .bind. Given > that a bound function has strictly more info than an unbound one, > I wouldn't expect that (I expected a bound function to be roughly > the same as an unbound function that does not use "this"). Unless > there is no special casing for the just-add-this case, and .bind is > always treated as a non-standard (meta-level) call. > > While playing with test-code, I also found that v8 does a lot better > than other engines when using an .apply-based .bind emulation. > > Can anyone explain what is going on with .bind, .apply and the > performance hits? > > The TypeScript issue is https://typescript.codeplex.com/workitem/1322 . > My test code (*) is attached there as "bind-for-arrows.html". > > Claus > http://clausreinke.github.com/ > > (*) I also tried to make a jsperf test case, but the way jsperf > runs the loop seems to prevent the optimization that makes > v8 look good for the .apply-based bind. > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
