Why can't I add a Dog Face (u+1f436) field to my object without using a String?

Question

This:

var foo = {
  : true //Truely adorable
};

Gives me an Illegal Character error on Firefox and Chrome. However,

var foo = {
  '' : true
};

Works perfectly. Why?
(You can also answer for a wider set of Unicode characters, but I really want to know more about Dog)

Here's a great explanation of what's allowed and what's not: https://mathiasbynens.be/notes/javascript-identifiers — CodingIntrigue, Jun 23 '15 at 14:02
Because its not in a unicode range of allowed identifier characters. The latter example is just a string containing the character. See [What characters are valid for JavaScript variable names?](http://stackoverflow.com/questions/1661197/what-characters-are-valid-for-javascript-variable-names) — Alex K., Jun 23 '15 at 14:03

score 6 · Accepted Answer · edited Jun 24 '15 at 01:41

6

As the ECMAScript standard defines, valid identifiers must start with a Unicode code point with the Unicode property ID_Start.

You may use any of these code points as first character of your identifier:

edited Jun 24 '15 at 01:41

Remy Lebeau

answered Jun 23 '15 at 14:11

Hauke P.

Okay I found the Hiragana (`ちえん`) but it's still 3 characters so meh. Update: One character! In traditional chinese : `狗` (U+72D7). – Kyll Jun 23 '15 at 14:38
Try an [Egyptian hieroglyph](http://www.unicode.org/charts/PDF/U13000.pdf). Not sure if your IDE (or even your browser) will render them though. – Hauke P. Jun 23 '15 at 14:42

1 Answers1