longs appear to be converted to floats internally, silently losing precision

[ajitgeorge]

ageorge@machine:~ (master)$ echo 1342647857257299304 | /grid/bin/jq .
1342647857257299200
ageorge@machine:~ (master)$ ipython
Python 2.7.3 (default, Aug  1 2012, 05:14:39) 
Type "copyright", "credits" or "license" for more information.

IPython 0.12.1 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

In [1]: float(1342647857257299304)
Out[1]: 1.3426478572572992e+18

[stedolan]

Yep. Doubles actually, so we've enough precision to hold 32 bit ints or milliseconds-since-1970 timestamps without loss of precision. The JSON spec doesn't specify number precision, so it's hard to tell what the correct behaviour is here, but most Javascript implementations use double precision.

You get the same output in the javascript console on chrome.