Note that this proposal isn't currently under consideration for inclusion in ES.next, but the answer to you question is below On Jan 22, 2012, at 10:59 PM, Mathias Bynens wrote:
> http://wiki.ecmascript.org/doku.php?id=strawman:support_full_unicode_in_strings#unicode_escape_sequences > states: > >> To address this issue, a new form ofUnicodeEscapeSequence is added that is >> explicitly tagged as containing var variable number (up to 8) of hex digits. >> The new definition is: >> >> UnicodeEscapeSequence :: >> u HexDigit HexDigit HexDigit HexDigit >> u{ HexDigit HexDigitopt HexDigitopt HexDigitopt HexDigitopt HexDigitopt >> HexDigitopt HexDigitopt } >> >> The \u{ } extended UnicodeEscapeSequence is a syntactic extension that is >> only recognized after explicit versioning opt-in to the extended “Harmony” >> syntax. > > Why up to 8 hex digits? Shouldn’t 6 hex digits suffice to represent > every possible Unicode character (in the range from 0x0 to 0x10ffff)? > > Is this a typo or was this done intentionally to be future-compatible > with potential Unicode additions? Just as the current definition of string specifies that a String is a sequence of 16-bit unsigned integer values, the proposal would specify that a String is a sequence of 32-bit unsigned integer values. In neither cause is it required that the individual String elements must be valid Unicode code point or code units. 8 hex digits are required to express a the full range of unsigned 32-bit integers. Allen _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
