Sorry, missed one question in there:
> -----Original Message----- > From: [email protected] [mailto:es-discuss- > [email protected]] On Behalf Of Brian Terlson > Sent: Wednesday, December 26, 2012 4:13 PM > To: Brendan Eich > Cc: Charles McCathie Nevile; [email protected] > Subject: RE: Real World Func Decl in Block Scope Breakages > > Hi Brendan, > > Responses inline. > > > -----Original Message----- > > From: Brendan Eich [mailto:[email protected]] > > Sent: Wednesday, December 26, 2012 3:27 PM > > To: Brian Terlson > > Cc: [email protected]; Charles McCathie Nevile > > Subject: Re: Real World Func Decl in Block Scope Breakages > > > > Brian Terlson wrote: > > > 20 sites, however, will likely be broken by this change in some way. > > > There is also a chance that the tool used to identify breakages has > > > missed some code that will breka. > > > > > > Below are some examples of code on the web today that will be broken. > > > For each I include a snippet of code that is heavily edited in an > > > attempt to convey the pattern used and the developer intent. I also > > > attempt to identify what functionality will actually be broken. > > > > > > > Thanks for the snippets. Some questions interspersed below. > > > > > Most of the breakages occur in non-library code, with two exceptions: > > > qTip 1.0, and thickbox 3. > > > > > > # http://ninemsn.com.au > > > > > > RenderModal = function () { > > > > > > if (x) { // is an array of shortcuts that can be added. Is > > > statically non-empty. > > > > > > function K() { > > > > > > // process the array of shortcuts in some way > > > > > > } > > > > > > } > > > > > > K(); > > > > > > }; > > > > > > > Since x evaluates as truthy no matter what (even an empty array is an > > object, therefore truthy), this is equivalent to > > > > RenderModal = function () { > > > > function K() { > > > > // process the array of shortcuts in some way > > > > } > > > > K(); > > > > }; > > > > > > but of course it lies outside of ES6's function-in-block semantics, > > yet still in the intersection of Firefox and IE/IE-emulating-browsers. > > > > > # http://yandex.ru > > > > > > if (_ycssjs("BaH0Fmmo2Sg24lRmTPrK0B8qpaA")) { > > > > > > function cp(g, c, d) { /* ...*/ } > > > > > > function csh_ifgsid(c, b) { /*...*/ } } > > > > > > // ... thousands of lines of code ... > > > > > > > This "then" block presumably closes here, before: > > > > > if (_ycssjs("rO+QIoSf2L0NwDn6vjJjy+27nxI")) { > > > > > > function news() { > > > > > > csh_if_gsid(); > > > > > > } > > > > > > } > > > > > > if (_ycssjs("YRPF0QVjJmhRiKRu6cvi3YXqYo8")) { > > > > > > // ... bunch of stuff ... > > > > > > cp(); > > > > > > } > > > > > > > Somehow the "if" conditions are logically connected such that no calls > > to an undefined identifier occur! Blech. > > > > > ## Scenario > > > > > > > > > Unknown > > > > > > > Indeed! Cc'ing Chaals in case he can shed light. > > > > > # > > > http://g.espncdn.com/nfl-primetime- > > payoff/en/module/entry?matchupid=47 > > > 8 > > > > > > if (isIE && isWin) { > > > > > > // ... > > > > > > } else { > > > > > > function JSGetSwfVer(i){ > > > > > > // ... > > > > > > } > > > > > > } > > > > > > function checkFlash(myRev) { > > > > > > // ... > > > > > > if (isIE && isWin) { > > > > > > // ... > > > > > > } else { > > > > > > aV = JSGetSwfVer(rV); > > > > > > } > > > > > > } > > > > > > ## Scenario > > > > > > Can't find a page which uses this code. > > > > > > > Can you say how many of the 20 cases involve actual live code using > > the function-in-pre-ES6-block code? > > Just going by the snippets that have a known scenario rather than unknown, > looks like 10/20. For the others, I do not know for sure whether the snippet > is > dead code or not. If you have any suggestions for how I could determine this > more easily than heavily using the site under instrumentation I can look into > collecting that data before the Jan meeting. > > > > > > # http://www.t-online.de > > > > > > if (!Adition_Environment) { > > > > > > var Adition_Environment = (function () { > > > > > > var _this = {}; > > > > > > // ... > > > > > > _this.getPrf = function (cuId) { > > > > > > var prf = ""; > > > > > > try { > > > > > > prf = Adition_Prfstr(cuId); > > > > > > } catch (e) { } > > > > > > return prf; > > > > > > }; > > > > > > // ... > > > > > > })(); > > > > > > } > > > > > > // snip 1k lines > > > > > > if (typeof Adition_Prfstr == "undefined") { > > > > > > function Adition_Prfstr(ADITION_CONTENTUNIT_ID) { > > > > > > // ... > > > > > > } > > > > > > } > > > > > > ## Scenario > > > > > > Required to display advertisements on the page. > > > > > > > Heinous. > > > > > # http://manormystery.com > > > > > > if (!window._ate) { > > > > > > window._ate = { /* ... */ }; > > > > > > function addthis_open() { /* ... */ } } else { _ate.inst++; } > > > > > > > > > > Did you snip the closing brace for the "then" block left open, the one > > for "if (!window._ate)"? The formatting is really bad due to a botched HTML-->plaintext conversion but it's there after the addthis_open decl. > > > > > if (_atc.abf) { > > > > > > addthis_open(document.getElementById("ab"), "emailab", > > > window.addthis_url || "[URL]", window.addthis_title || "[TITLE]"); } > > > > > > ## Scenario > > > > > > Social sharing popups broken at least. This may be a general utility > > > used in a number of places. > > > > > > > On the other hand, the snippet seems like a mis-coding of > > > > if (!window._ate) { > > > > window._ate = { /* ... */ }; > > > > } > > > > function addthis_open() { /* ... */ } } else { _ate.inst++; } > > > > > > if (_atc.abf) { > > > > addthis_open(document.getElementById("ab"), "emailab", > > window.addthis_url || "[URL]", window.addthis_title || "[TITLE]"); } > > > > ... > > } > > > > I'd try to evangelize the owner of this code. > > > > > # http://manhunt.net (NSFW, DO NOT VISIT AT WORK) > > > > > > /** @todo isFlashInstalled() should probably be gotten by include > > > from js/cmmn/flashDetect.js or upfunc.js. */ > > > > > > if (typeof isFlashInstalled == 'undefined') { > > > > > > function isFlashInstalled() { > > > > > > var requiredMajorVersion = 6; // Major version of Flash required > > > > > > var requiredMinorVersion = 0; // Minor version of Flash required > > > > > > var requiredRevision = 0; // Minor version of Flash required > > > > > > var s = new SWFObject(); > > > > > > if (!s) return false; > > > > > > var version = s.installedVer; > > > > > > if (!version) return false; > > > > > > return (version.major >= requiredMajorVersion && version.minor >= > > > requiredMinorVersion && version.rev >= requiredRevision); > > > > > > } > > > > > > } > > > > > > isFlashInstalled(); > > > > > > > Here is the simplest example of a pre-ES6 Firefox/IE+clones > > intersection: function-in-block with hoisting to top of outer function > > or global scope *and* SpiderMonkey's assignment-like runtime binding > > both work the same, provided the use(s) of the function's name all > > occur after any such assignment (in the SpiderMonkey in Firefox scenario). > > > > There's no control flow relation in general, e.g. dominance. However > > in this case the "if (typeof isFlashInstalled == 'undefined')" head > > could, to a sufficiently smart CFG analyzer, imply that > > isFlashInstalled() post-dominates some kind of "definition" of that name. > > > > Ok, enough so far to say a few things: > > > > 1. We have time and (among the bigs involved in ES6) try evangelization. > > Evangelization can be crowd-sourced too, and can be more effective > > when done that way. > > > > 2. We have some terrible choices, even if ES6's function-in-block > > semantics require "use strict". That leaves the above mess a de-facto > > standard which has never been specified. Specifying the sloppy-mode > > intersection is going to be ugly and a time-sink. > > > > 3. The carrot of function-in-block may be sweet -- we have evidence in > > all the good sites your crawl found that are not the insane 20 -- but > > whether "use strict"; required before all such ES6 function-in-block > > uses would be a stick remains to be investigated. Did you check for > > "use strict" or actual enabled- > > in-IE10 strict mode among the sites you found that declare functions > > in blocks? > > Programmers do seem to want func decls in block scope a lot more than I > expected, although I wouldn't necessarily call all non-breaking instances of > it I > found "sane" (eg. the decls I found in while/for statements...), just less > insane :) > > I didn't check for "use strict". I will work on capturing this data at least > in time > for the Jan meeting. > > As far as IE doc modes, 15/19 are in standards mode (Zoompanel.com, > Kankan.com, 163.com, and Verizon.com run in some compat mode). Didn't > check the NSFW site. > > > > > /be > > > > > > > > > _______________________________________________ > 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
