Are numerals valid as names in JSON

Question

The following snippet executes in IE 10 JS console and in Chromes JS console. fiddle

 alert({123:"ABC"}[123]);

However when run this through a linter (for example jslint.com) it complains.

When I read the documentation in json.org I understand the following enter image description here

to mean that it is incorrect to use numbers as names in a JSON object. So does this mean that at least the V8 and Chakra engine are incorrect? Or does this have something to do with strict mode(if it does, it doesn't seem to have any effect when i test it in node)?

Property names ALWAYS have to be quoted in JSON. It doesn't matter what they contain. — Barmar, Apr 14 '15 at 10:26
Internally those numerals will be converted into strings by it's `toString()`. So, it will be accessed fine. But it's better to use strings as property names. — Vigneswaran Marimuthu, Apr 14 '15 at 10:27
@VigneswaranMarimuthu do you know where I could find the documentation for that? — Daniel Figueroa, Apr 14 '15 at 10:28
@DanielFigueroa Check out https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Working_with_Objects - **An object property name can be any valid JavaScript string, or anything that can be converted to a string, including the empty string.**. i am trying to find one more link. Will post that soon — Vigneswaran Marimuthu, Apr 14 '15 at 10:30
@Barmar Isn't it still an object, which I thought was more or less just the same as JSON? — Daniel Figueroa, Apr 14 '15 at 10:31
@DanielFigueroa https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_Accessors --- Check under **Property Names** — Vigneswaran Marimuthu, Apr 14 '15 at 10:32
possible duplicate of [Javascript object Vs JSON](http://stackoverflow.com/questions/8294088/javascript-object-vs-json) — Daniel Figueroa, Apr 14 '15 at 10:34

score 3 · Accepted Answer · answered Apr 14 '15 at 10:34

3

You're confusing Javascript literal syntax with JSON syntax. JSON is a restricted subset of Javascript literal syntax.

The specification of ECMAScript object initialisers can be found here. It contains the following production:

PropertyName :
    IdentifierName
    StringLiteral
    NumericLiteral

So a number is allowed as a property name.

answered Apr 14 '15 at 10:34

Barmar

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Thanks! I just found this question: http://stackoverflow.com/questions/8294088/javascript-object-vs-json which also explains it. – Daniel Figueroa Apr 14 '15 at 10:35

Bram · Answer 2 · 2015-04-14T10:32:29.740

0

The following would be correct:

var jsonString = {"123":"ABC"};
alert(jsonString[123]);

You have to add quotes.

You can find the documentation here http://www.json.org/

edited Apr 14 '15 at 10:32

answered Apr 14 '15 at 10:26

Bram

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Pavel Gatnar · Answer 3 · 2015-04-14T10:35:16.543

0

you can use numeric names as strings, e.g. {"123":"ABC"} is a valid JSON while {123:"ABC"} is a valid Javascript expression

edited Apr 14 '15 at 10:35

answered Apr 14 '15 at 10:27

Pavel Gatnar

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Are numerals valid as names in JSON

3 Answers3