"\08" is ill formed in ECMA262

# Yusuke SUZUKI (12 years ago)

Hello all,

Seeing ECMA262 section 7.8.4,

EscapeSequence ::

CharacterEscapeSequence
0 [lookahead ∉ DecimalDigit]
HexEscapeSequence
UnicodeEscapeSequence

Because of "[lookahead ∉ DecimalDigit]", strictly speaking, "\08" / "\09" is ill formed StringLiteral. But engines in the wild, V8, SpiderMonkey, JSC accepts this form and recognize it as "\x008".

To bridege the gap, I think it is better to introduce this form to the spec officially.

, Yusuke Suzuki

Hello all,

Seeing ECMA262 section 7.8.4,

EscapeSequence ::
>     CharacterEscapeSequence
>     0 [lookahead ∉ DecimalDigit]
>     HexEscapeSequence
>     UnicodeEscapeSequence


Because of "[lookahead ∉ DecimalDigit]", strictly speaking, "\08" / "\09"
is ill formed StringLiteral.
But engines in the wild, V8, SpiderMonkey, JSC accepts this form and
recognize it as "\x008".

To bridege the gap, I think it is better to introduce this form to the spec
officially.

---
Regards,
Yusuke Suzuki
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# Mathias Bynens (12 years ago)

Agreed. Let's loosen the restriction to octal digits only, to match reality.

Filed a bug: ecmascript#1553

Also filed it here, in case it's not accepted for ECMAScript: whatwg/javascript#12

On 8 Jun 2013, at 19:01, Yusuke SUZUKI <utatane.tea at gmail.com> wrote:

> Hello all,
> 
> Seeing ECMA262 section 7.8.4,
> 
> EscapeSequence ::
>     CharacterEscapeSequence
>     0 [lookahead ∉ DecimalDigit]
>     HexEscapeSequence
>     UnicodeEscapeSequence
> 
> Because of "[lookahead ∉ DecimalDigit]", strictly speaking, "\08" / "\09" is ill formed StringLiteral.
> But engines in the wild, V8, SpiderMonkey, JSC accepts this form and recognize it as "\x008".
> 
> To bridege the gap, I think it is better to introduce this form to the spec officially.

Agreed. Let’s loosen the restriction to octal digits only, to match reality.

Filed a bug: https://bugs.ecmascript.org/show_bug.cgi?id=1553

Also filed it here, in case it’s not accepted for ECMAScript: https://github.com/whatwg/javascript/issues/12