My implication was that it'd only be available in the `if` (if declared with `let`/`const`). -----
Isiah Meadows [email protected] Looking for web consulting? Or a new website? Send me an email and we can get started. www.isiahmeadows.com On Wed, Mar 21, 2018 at 6:25 PM, Sebastian Malton <[email protected]> wrote: > Sorry if I missed a message but would such an initialization be only > available in the first `if` block or also in the subsequent `else if` and > `else` blocks? > > Sebastian Malton > > > Original Message > From: [email protected] > Sent: March 21, 2018 6:18 PM > To: [email protected] > Cc: [email protected]; [email protected] > Subject: Re: Proposal: if variable initialization > > I'm personally very much *for* this `if (var ...; cond) { ... }` > syntax. I couldn't tell you how many times I would've liked something > to that effect, since that's probably one of my biggest areas of > boilerplate. > > I would also be in favor of `if (var ...) { ... }` as a shorthand that > guards `!= null` the expression result (pre-match), since that's about > 90% of my use cases for it. There *is* a potential area of ambiguity > in sloppy for `if ( let [ x ] = y )`, since that would be currently > parsed as `var tmp = y; let[x] = tmp; if (tmp) { ... }`, but I doubt > breaking that would be of much web compat risk. (A similar ambiguity > existed with `for (let [`, but that break didn't cause many issues.) > ----- > > Isiah Meadows > [email protected] > > Looking for web consulting? Or a new website? > Send me an email and we can get started. > www.isiahmeadows.com > > > On Wed, Mar 21, 2018 at 2:47 PM, Mike Samuel <[email protected]> wrote: >> >> >> On Wed, Mar 21, 2018 at 1:27 PM, Sebastian Malton <[email protected]> >> wrote: >>> >>> Because block-level scoping is a very good way to avoid certain bugs and >>> is easier to reason about. Especially when considering project successors. >> >> >> +1. function-scoped variables in loop bodies caused tons of bugs before >> let-scoped variables and were a main motivating case. >> >> var i; >> for (i = 0; i < arr.length; ++i) { >> f(function () { /* Do something with */ arr[i]; }); >> } >> >> vs >> >> for (let i = 0; i < arr.length; ++i) { >> f(function () { /* Do something with */ arr[i]; }); >> } >> >> Yes, linters got pretty good at finding uses of closed-over variables >> modified in a loop, but the workarounds were not ideal. >> >> var i; >> for (i = 0; i < arr.length; ++i) { >> f(function (i) { return function () { /* Do something with */ arr[i]; } >> }(i)); >> } >> >> Block scoping is just better for code that uses loops, variables, and >> function expressions. >> >> >> _______________________________________________ >> 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
