[whatwg] [JavaScript / Web ECMAScript] Dropping the “escaped reserved words” compatibility requirement

Mathias Bynens mathias at qiwi.be
Thu Jul 5 01:47:46 PDT 2012

http://mathias.html5.org/specs/javascript/#escaped-reserved-words says:

> JavaScript implementations must support ECMAScript identifiers that unescape
> to a reserved word, as long as at least one character is escaped using a
> Unicode escape sequence.
> For example, var var; throws a syntax error, but e.g. var v\u0061r; works
> fine.
> Subsequent use of such identifiers must also have at least one character
> escaped (otherwise the reserved word will be used instead), but it doesn’t
> have to be the same character(s) that were originally used to create the
> identifier.
> For example, var v\u0061r = 42; alert(va\u0072); alerts 42.

One year ago, all browsers except IE fulfilled this compatibility requirement.

Half a year ago Firefox dropped this non-standard addition
(https://bugzilla.mozilla.org/show_bug.cgi?id=694360) and hasn’t seen any
compatibility issues since.

Has the time come to drop this compatibility requirement?

More information about the whatwg mailing list