Editing JSON (section)

=== Character encoding ===
Although Crockford originally asserted that JSON is a strict subset of [[JavaScript]] and [[ECMAScript]],<ref>{{cite web|url=http://www.json.org/js.html |title=JSON in JavaScript |date=2016-07-10 |access-date=2016-08-13 |author=Douglas Crockford |url-status=dead |archive-url=https://web.archive.org/web/20160710230817/http://www.json.org/js.html |archive-date=2016-07-10 |quote=JSON is a subset of the object literal notation of JavaScript. }}</ref> his specification actually allows valid JSON documents that are not valid JavaScript; JSON allows the [[Unicode#Newlines|Unicode line terminators]] {{unichar|2028|LINE SEPARATOR}} and {{unichar|2029|PARAGRAPH SEPARATOR}} to appear unescaped in quoted strings, while ECMAScript 2018 and older do not.<ref name="json-2028">{{cite web|url=http://timelessrepo.com/json-isnt-a-javascript-subset|title=JSON: The JavaScript subset that isn't|author=Holm, Magnus|date=15 May 2011|publisher=The timeless repository|access-date=23 September 2016|archive-date=May 13, 2012|archive-url=https://web.archive.org/web/20120513012409/http://timelessrepo.com/json-isnt-a-javascript-subset|url-status=dead}}</ref><ref name=ECMATC39/> This is a consequence of JSON disallowing only "control characters". For maximum portability, these characters are backslash-escaped.

JSON exchange in an open ecosystem must be encoded in [[UTF-8]].<ref name="rfc8259">{{cite journal | url=https://tools.ietf.org/html/rfc8259 | title= The JavaScript Object Notation (JSON) Data Interchange Format | publisher=IETF | date= December 2017 | doi= 10.17487/RFC8259 | access-date=16 February 2018| editor-last1= Bray | editor-first1= T | last1= Bray | first1= T. | s2cid= 263868313 }}</ref> The encoding supports the full Unicode character set, including those characters outside the [[Basic Multilingual Plane]] (U+0000 to U+FFFF). However, if escaped, those characters must be written using [[UTF-16#Code points from U+010000 to U+10FFFF|UTF-16 surrogate pairs]]. For example, to include the [[Emoji]] character {{unichar|1F610|NEUTRAL FACE}} in JSON:

<syntaxhighlight lang="javascript">
{ "face": "😐" }
// or
{ "face": "\uD83D\uDE10" }
</syntaxhighlight>

JSON became a strict subset of ECMAScript as of the language's 2019 revision.<ref name=ECMATC39/><ref name=ECMATC39Stage4/>