How to get the real UTC timestamp (client independent)?

问题:

Is there a way to get the real current UTC timestamp without being dependent on the client's time which might not be set correctly on every client?

I know with JavaScript's getTime() I can get the UTC timestamp in milliseconds. It's independent of the client's timezone, but I think it's dependent of the client's current time.

I'm trying to make a live clock that shows the real UTC time, so it shouldn't matter if the client's time is set correctly or not for it to be correct.

回答1:

Get this JSON:

http://json-time.appspot.com/time.json 

Or

http://www.timeapi.org/utc/now 

Also you can get it from your own server if you have one.

For an example of the first one (with interval):

HTML:

<div id="time">Click the button</div> <button id="gettime">Get the time</button> 

JAVASCRIPT (With JQuery):

$("#gettime").click(function() { setInterval(ajaxCalltoGetTime, 1000); });   function ajaxCalltoGetTime() { $.ajax({ type: "GET",     url: 'http://json-time.appspot.com/time.json',     dataType: 'jsonp' }) .done(function( msg ) {     $("#time").html(msg.hour + ":" + msg.minute + ":" + msg.second ); }); 

JSFiddler: http://jsfiddle.net/op8xdsrv/

回答2:

You can trust your server's clock*. Just send the current UNIX timestamp from the server to the client. Then can use in JavaScript Date(value) constructor.

<script> var serverTime = new Date(<? php echo time(); ?> * 1000); console.log(     serverTime.getUTCFullYear(),      serverTime.getUTCMonth() + 1,      serverTime.getUTCDate(),      serverTime.getUTCHours(),      serverTime.getUTCMinutes(),      serverTime.getUTCSeconds() ); // use this time to seed your JavaScript clock </script> 

* Generally speaking, servers periodically synchronize their time with a time provider.

回答3:

you can use timeanddate api to get date and time without dependending on client machine or your server in php. Then send it to javascript.

文章来源: How to get the real UTC timestamp (client independent)?