def date_to_timestamp(date: pd.DatetimeIndex):
"""Convert a pandas datetime to a javascript timestamp.
This aims to match the timezone handling semantics
used in Vega and Vega-Lite.
Parameters
----------
timestamp : float
The unix epoch timestamp.
Returns
-------
date : pd.DatetimeIndex
The timestamps to be converted
See Also
--------
date_to_timestamp : opposite of this function
"""
if date.tzinfo is None:
date = date.tz_localize(tzlocal())
try:
# Works for pd.Timestamp
return date.timestamp() * 1000
except AttributeError:
# Works for pd.DatetimeIndex
return date.astype('int64') * 1E-6
