Whole seconds from now until the local datetime target (a string
from an <input type="datetime-local">, or a Date). Returns null
for an invalid value or any time at/before now — the caller uses
null to mean "nothing to pause for." A bare date-time string with no
timezone is interpreted as local time, matching the picker.
Whole seconds from
nowuntil the local datetimetarget(a string from an<input type="datetime-local">, or aDate). Returnsnullfor an invalid value or any time at/beforenow— the caller usesnullto mean "nothing to pause for." A bare date-time string with no timezone is interpreted as local time, matching the picker.