{"action":"created","issue":{"url":"https://api.github.com/repos/tc39/ecma262/issues/289","labels_url":"https://api.github.com/repos/tc39/ecma262/issues/289/labels{/name}","comments_url":"https://api.github.com/repos/tc39/ecma262/issues/289/comments","events_url":"https://api.github.com/repos/tc39/ecma262/issues/289/events","html_url":"https://github.com/tc39/ecma262/issues/289","id":126850865,"number":289,"title":"A.p.join on cyclic arrays does not reflect web reality","user":{"login":"rossberg-chromium","id":4247099,"avatar_url":"https://avatars.githubusercontent.com/u/4247099?v=3","gravatar_id":"","url":"https://api.github.com/users/rossberg-chromium","html_url":"https://github.com/rossberg-chromium","followers_url":"https://api.github.com/users/rossberg-chromium/followers","following_url":"https://api.github.com/users/rossberg-chromium/following{/other_user}","gists_url":"https://api.github.com/users/rossberg-chromium/gists{/gist_id}","starred_url":"https://api.github.com/users/rossberg-chromium/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/rossberg-chromium/subscriptions","organizations_url":"https://api.github.com/users/rossberg-chromium/orgs","repos_url":"https://api.github.com/users/rossberg-chromium/repos","events_url":"https://api.github.com/users/rossberg-chromium/events{/privacy}","received_events_url":"https://api.github.com/users/rossberg-chromium/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":4,"created_at":"2016-01-15T10:55:39Z","updated_at":"2016-01-15T21:50:06Z","closed_at":null,"body":"Browsers have special measures for dealing with cyclic arrays in the `A.p.join` operator (and by extension, `A.p.toString`). Chrome, IE, Firefox, & Safari all behave as follows:\r\n```\r\na = [1,,2]\r\na[1] = a\r\na.toString() === \"1,,2\"\r\n```\r\nThat is, they detect the cycle and replace it with the empty string. This is not reflected by the spec, which would require toString to diverge.\r\n\r\nShould browsers change, or the spec?"},"comment":{"url":"https://api.github.com/repos/tc39/ecma262/issues/comments/172104159","html_url":"https://github.com/tc39/ecma262/issues/289#issuecomment-172104159","issue_url":"https://api.github.com/repos/tc39/ecma262/issues/289","id":172104159,"user":{"login":"bterlson","id":11236,"avatar_url":"https://avatars.githubusercontent.com/u/11236?v=3","gravatar_id":"","url":"https://api.github.com/users/bterlson","html_url":"https://github.com/bterlson","followers_url":"https://api.github.com/users/bterlson/followers","following_url":"https://api.github.com/users/bterlson/following{/other_user}","gists_url":"https://api.github.com/users/bterlson/gists{/gist_id}","starred_url":"https://api.github.com/users/bterlson/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bterlson/subscriptions","organizations_url":"https://api.github.com/users/bterlson/orgs","repos_url":"https://api.github.com/users/bterlson/repos","events_url":"https://api.github.com/users/bterlson/events{/privacy}","received_events_url":"https://api.github.com/users/bterlson/received_events","type":"User","site_admin":false},"created_at":"2016-01-15T21:50:06Z","updated_at":"2016-01-15T21:50:06Z","body":"Chakra's implementation is to essentially keep a seen list in the current Realm. I suppose that would work here as well."}}