D3v4: d3.timeParse fails with UNIX epoch seconds (%s)

My dataset includes UNIX timestamps, such as "1509392160". I can't seem to parse those using d3.timeParse("%s"), which returns null.

Checking the reverse process with d3.timeFormat fails me as well. The official example and all other format strings work:

var formatTime = d3.timeFormat("%B %d, %Y");
formatTime(new Date); // -> "June 30, 2015"

However, formatting to UNIX (milli)seconds just returns "s" or "Q" for "%s" and "%Q":

var formatTime = d3.timeFormat("%s");
formatTime(new Date); // -> "s"

Using D3 v4.11.0 btw. What am I missing?

Copyright Notice：Content Author:「gl03」，Reproduced under the CC 4.0 BY-SA copyright license with a link to the original source and this disclaimer.
Link to original article：https://stackoverflow.com/questions/47043555/d3v4-d3-timeparse-fails-with-unix-epoch-seconds-s