128-bit IEEE DFP

Brendan Eich brendan at mozilla.org
Sat Mar 17 11:36:34 PDT 2012

Yes, Sam Ruby prototyped a new Decimal built-in for SpiderMonkey, with 
operators. This was in mid-2008 when ES4 was going down. See


TC39 rejected hardcoding IEEE DFP into JS at the 2008 fall "Kona" meeting:


Waldemar: "Decimal is out because the spec isn't ready and there are 
some problems that are not small spec errors -- generic behavior of 
functions, etc."

Some discussion lingered on:


The plan since then is to add value types or proxies to the language, so 
that Decimal, Complex, etc. with operators and literals for good 
usability may be added by library authors. See




See also (from 2010) a hardcoded bignums strawman:



Andrew Paprocki wrote:
> I see there was a bunch of work done to possibly introduce 128-bit
> IEEE754r DFP back in the ES4 days:
> http://wiki.ecmascript.org/doku.php?id=proposals:decimal&s=decimal
> Has any work been done since ES4 to introduce a DFP type?
> -Andrew
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