Convert PHP Unix Timestamp to Javascript Timestamp format

Question

I'm throwing a unix timestamp from my php to my javascript and I noticed that PHP and Javascript timestamps are different (seconds vs. milliseconds) from the epoch.

What I'm basically doing is to echo the php unixtime then add 3 zeroes (as to simply multiply it by 1000) but I noticed that when I check it, it shows that the time is off by around 4-8 hours.

I am using canvas.js and I need to convert it using the unix timestamp

For example:

1434183780

Jun 13 2015 8:23AM

I add 3 zeroes

1434183780000

echo "{ x:".$chartData[$loop]['time']."000 , y:1 }";

and what happens is the time becomes:

Jun 13 2015 16:23PM

Everything is working fine except that the time becomes completely distorted.

How could I make it work without the time being changed once I put it on javascript? I'd prefer to keep it in unixtime as I still use it in that format when I do something else with it.

Answer 1

This sounds just like a time zone issue.

A Unix timestamp is always a point in time in UTC .

When displaying it in a format like "Jun 13 2015 8:23AM" you are always using a certain time zone to display it as such. The reason the time is being displayed as "16:23PM" is because a time zone other than you expect is being used to display the Unix timestamp.

So the solution is simply making sure you're picking the correct time zone when displaying the timestamp.

If you're using the JavaScript Date object and you mean to use UTC, you can try using a method like toUTCString() :

console.log(new Date(1434183780000).toUTCString());
// Output: Sat, 13 Jun 2015 08:23:00 GMT

Date supports only the local time zone or UTC. If you want to construct your own formatted string in UTC, you can use the methods in Date starting with getUTC*() , like getUTCHours() or getUTCDate() .

See more info on the Date object in: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date