Path: csiph.com!weretis.net!feeder8.news.weretis.net!news.mb-net.net!open-news-network.org!.POSTED.50.236.197.178.dynamic.wless.lssmb00p-cgnat.res.cust.swisscom.ch!not-for-mail From: Thomas 'PointedEars' Lahn Newsgroups: comp.lang.javascript Subject: Re: Referencing an object prop with a string Date: Tue, 02 Feb 2021 23:50:18 +0100 Organization: PointedEars Software (PES) Lines: 61 Message-ID: <2081055.NgBsaNRSFp@PointedEars.de> References: <5793bf43-6506-4351-bdca-3d59d740c5e5n@googlegroups.com> <806120824.0ifERbkFSE@PointedEars.de> Reply-To: Thomas 'PointedEars' Lahn Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8Bit Injection-Info: gwaiyur.mb-net.net; posting-host="50.236.197.178.dynamic.wless.lssmb00p-cgnat.res.cust.swisscom.ch:178.197.236.50"; logging-data="11742"; mail-complaints-to="abuse@open-news-network.org" User-Agent: KNode/4.14.10 Cancel-Lock: sha1:UaitrKq4Lp/Y8wVMhd3NcbmD5qE= X-Face: %i>XG-yXR'\"2P/C_aO%~;2o~?g0pPKmbOw^=NT`tprDEf++D.m7"}HW6.#=U:?2GGctkL,f89@H46O$ASoW&?s}.k+&. On Monday, February 1, 2021 at 9:07:06 PM UTC-6, Thomas 'PointedEars' Lahn > wrote: >> Michael Haufe (TNO) wrote: >> > let walk = (o, path)=>path.split('.').reduce((o,k)=>o && o[k], o); >> This does not work if the property name contains `.'. The approach to use >> Array.prototype.reduce() is an elegant one, though, and can be applied to >> supporting a path array (too), which solves that problem: >> >> let walk = (o, path) => path.reduce((o, k) => o && o[k], o); > > I wonder if a variant of JSONPath could be promoted into the language > proper. Yes, I am not particularly fond of Stefan Goessners syntax choices either. While I could perhaps live with “@” instead of “.”, coming from the command shell I find “..” to access *subordered* items very counter-intuitive (I also did with E4X). Why did he not propose and implement the familiar XPath syntax? For example, I see no good reason to propose ”$” instead of “/”. > I tried in the early ES5 days to convince the committee but there > were bigger fish to fry at the time. ACK. > With Symbols and the spread operator, it may be harder to get a proposal > through. What exactly do you mean? One problem I see is that there is not really a need for it anymore (or is there?): You can write now (and at least *execute* much more efficiently) obj?.store?.book?.filter((book) => book.price < 10) .map((book) => book.title) || [] instead of jsonPath(obj, '$.store.book[?(@.price < 10)].title') Which reminds me of LINQ which solves similar problems. > At least Slice Notation has a change of succeeding: > > Yes, I think that would be a useful and unproblematic addition. I would even like a[-1] as in Python (seriously, is there a use-case for properties named named “-1” in an *array*?). I added support for using negative indexes to access elements from the end of an array in JSX:array.js:BigArray with Proxy, and BigArray.prototype.get() to do it in a backwards-compatible way, about 5 years ago: -- PointedEars FAQ: | | Twitter: @PointedEars2 | Please do not cc me./Bitte keine Kopien per E-Mail.