Convert between a JavaScript Date object and a Unix timestamp

Unix timestamps are a number representing the number of seconds since the Unix epoch (January 1, 1970, 00:00:00 UTC). JavaScript Date objects are a number representing the number of milliseconds since the Unix epoch.

This means that you can convert between Date objects and Unix timestamps by dividing or multiplying by 1000.

const toTimestamp = date => Math.floor(date.getTime() / 1000);
const fromTimestamp = timestamp => new Date(timestamp * 1000);

toTimestamp(new Date('2024-01-04')); // 1704326400
fromTimestamp(1704326400); // 2024-01-04T00:00:00.000Z