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
