219275 2020-11-24 07:25:21 -0800 block scope + const + hoisted function using the const = ReferenceError 2020-12-01 17:21:12 -0800 1 1 1 Unclassified WebKit JavaScriptCore Safari 14 All iOS 12 RESOLVED DUPLICATE 163209 InRadar P2 Normal --- 1 jakub.g.opensource webkit-unassigned ashvayka fpizlo ross.kirsling webkit-bug-importer ysuzuki oldest_to_newest 1710002 0 jakub.g.opensource 2020-11-24 07:25:21 -0800 Open the following test page: > https://jg-testpage.netlify.app/safari/const-inside-if.html Its contents for reference: ``` <script> if (true) { const MY_CONST = 'MY_CONST'; function myFunction() { console.log(MY_CONST); } myFunction(); } </script> ``` Expected: > see "MY_CONST" logged Actual: > ReferenceError Other browsers' behavior: > "MY_CONST" is logged in latest Chrome, Firefox, EdgeLegacy 18 1710003 1 jakub.g.opensource 2020-11-24 07:26:18 -0800 I repro the issue on all stable versions of Safari from 14.0 down to 10.1 (didn't test more) 1710325 2 jakub.g.opensource 2020-11-27 09:35:44 -0800 Just a small update: it seems to work fine in Safari in strict mode, but not in sloppy mode. https://jg-testpage.netlify.app/safari/const-inside-if.html https://jg-testpage.netlify.app/safari/const-inside-if-strict.html Chrome 50+: OK both strict/sloppy mode Firefox 50+: OK both strict/sloppy mode Safari: OK strict mode, KO in sloppy mode 1711032 3 webkit-bug-importer 2020-12-01 07:26:14 -0800 <rdar://problem/71849401> 1711228 4 ross.kirsling 2020-12-01 17:21:12 -0800 Thanks for the report -- Annex B.3.3 non-conformance has been deprioritized for a long time, but I think there is intention to correct this in the near future. *** This bug has been marked as a duplicate of bug 163209 ***