To get timestamp in JavaScript we use
var ts = new Date().getTime()
What is the proper way to convert it to a Python datetime so far I use the following code
>>> jsts = 1335205804950
>>> dt = datetime.datetime.fromtimestamp(jsts/1000)
>>> dt
datetime.datetime(2012, 4, 24, 0, 30, 4)
I divide timestamp by 1000 because I get error like
ValueError Traceback (most recent call last)
1 d = datetime.datetime.fromtimestamp(a)
ValueError: year is out of range
Your current method is correct, dividing by 1000 is necessary because your JavaScript returns the timestamp in milliseconds, and datetime.datetime.fromtimestamp() expects a timestamp in seconds.
To preserve the millisecond accuracy you can divide by 1000.0, so you are using float division instead of integer division:
>>> dt = datetime.datetime.fromtimestamp(jsts/1000.0)
>>> dt
datetime.datetime(2012, 4, 23, 11, 30, 4, 950000)