Looking fwd to see bignum support in ES7 fingerscrossed
Bignums are good, in Dart as in other languages. On the agenda for "Harmony-era" ECMAScript, going back to 2009:
http://wiki.ecmascript.org/doku.php?id=strawman:bignums
More recent work generalizes value types into an extension mechanism for JS, so you can have built-in and user-defined numeric types with operators and literals.
Or are bignums and decimals the same thing? (not sure).
Most financial applications deal with currencies each of which had a smallest indivisible unit in the application, which makes bignums most appropriate. But bigdecimals (or even arbitrary precision rationals) may be preferred in certain financial applications.