[nly]

A binary double can hold any decimal value to 15 digits of precision, so as a serialisation format it's a bit of a non-issue... you just need to convert to decimal and round appropriately before doing any arithmetic where it matters.

And you're confusing JSON the format with typical implementations. Open a JSON file and you see decimal digits. There is no limit to the number of the digits in the grammar. Parsing these digits and converting them to binary doubles, for example, is actually slower than parsing them as decimals, because you have to do the latter anyway to accomplish the former. Almost all JSON libraries convert to binary (e.g. doubles) because of their ubiquitous hardware and software support...but some libraries like RapidJSON expose raw numeric strings out of the parser if you want to plug in a decimal library

[indymike]

> And you're confusing JSON the format with typical implementations. Open a JSON file and you see decimal digits. There is no limit to the number of the digits in the grammar. Parsing these digits and converting them to binary doubles, for example, is actually slower than parsing them as decimals, because you have to do the latter anyway to accomplish the former.

JSON spec for numbers: integer or float (implemented as a double precision float). JSON libraries read numbers as double precision float because that is the correct type for JSON numbers, not for any other reason.