What characters are valid for JavaScript variable names? -

can point me web page detailing characters can used naming javascript variable?

i want create small "extension library" non-javascript users here @ work (who seem squeamish when comes language). love how jquery , prototype have both use $ dollar sign, , since use jquery, i'm looking nice single-character symbol use.

i realize test out number of characters, i'm posing question many javascript sensei of world advice characters (even if valid) bad idea use (in consideration of future integration popular library, perhaps).

to quote valid javascript variable names, write-up summarizing relevant spec sections:

an identifier must start $, _, or character in unicode categories “uppercase letter (lu)”, “lowercase letter (ll)”, “titlecase letter (lt)”, “modifier letter (lm)”, “other letter (lo)”, or “letter number (nl)”.

the rest of string can contain same characters, plus u+200c 0 width non-joiner characters, u+200d 0 width joiner characters, , characters in unicode categories “non-spacing mark (mn)”, “spacing combining mark (mc)”, “decimal digit number (nd)”, or “connector punctuation (pc)”.

i’ve created a tool tell if string enter valid javascript variable name according ecmascript 5.1 , unicode 6.1:

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p.s. give idea of how wrong anthony mills' answer is: if summarize these rules in single ascii-only regular expression javascript, it 11,236 characters long. here is:

// es5.1 / unicode 6.1 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