The base date as a Date object or timestamp (number)
The timestamp in milliseconds since Unix epoch (1970-01-01), or NaN if invalid
// Get timestamp from Date object
const result = getTime(new Date("2024-01-01T00:00:00.000Z"));
// Returns: 1704067200000
// Get timestamp from numeric input (returns as-is if valid)
const result2 = getTime(1704067200000);
// Returns: 1704067200000
// Unix epoch
const result3 = getTime(new Date(0));
// Returns: 0
// Negative timestamp (before epoch)
const result4 = getTime(new Date("1969-12-31T00:00:00.000Z"));
// Returns: -86400000
// Invalid date returns NaN
const result5 = getTime(new Date("invalid"));
// Returns: NaN
Get the timestamp of the given date.
This function validates arguments before processing and returns the timestamp (milliseconds since Unix epoch) of the given date. Returns NaN for invalid input.