Convert UTC Epoch to Local Date

Problem

Converting a UTC epoch timestamp into a local date object can be challenging. The standard Date() constructor interprets epochs as local, leading to incorrect results when the timestamp is actually in UTC. Attempts to create a UTC object and adjust the time using setTime() or retrieve the UTC offset have proven unsuccessful.

Solution

A simpler solution exists to convert UTC epochs to local dates. Instead of manipulating dates directly, set a new date to the epoch (represented as 0) and add the UTC epoch units. For instance, to convert a UTC epoch in seconds (e.g., 1234567890) to a local time:

var utcSeconds = 1234567890;
var d = new Date(0); // Sets the date to the epoch
d.setUTCSeconds(utcSeconds);

The resulting date, d, will now represent the local time equivalent of the UTC epoch timestamp. In this example, the date would be: Fri Feb 13 2009 18:31:30 GMT-0500 (EST).