How to get the exact local time of client?

What is the best method to get the clients local time irrespective of the time zone of clients system? I am creating an application and i need to first of all get the exact time and date of the place from where the client is accessing. Even detecting the ip address of client system has a drawback or detecting the time zone of client system may be risky at times. So, is there any way out which could be really reliable and not vulnerable to error because displaying wrong time and date to client is something very embarassing.

In JavaScript? Just instantiate a new Date object

var now = new Date();

That will create a new Date object with the client's local time.

Nowadays you can get correct timezone of a user having just one line of code:

const timezone = Intl.DateTimeFormat().resolvedOptions().timeZone;

source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/DateTimeFormat/resolvedOptions

You can then use moment-timezone to parse timezone like:

const currentTime = moment().tz(timezone).format();

Try

let s= new Date().toLocaleString();

console.log(s);

If you want to know the timezone of the client relative to GMT/UTC here you go:

var d = new Date();
var tz = d.toString().split("GMT")[1].split(" (")[0]; // timezone, i.e. -0700

If you'd like the actual name of the timezone you can try this:

var d = new Date();
var tz = d.toString().split("GMT")[1]; // timezone, i.e. -0700 (Pacific Daylight Time)

UPDATE 1

Per the first comment by you can also use d.getTimezoneOffset() to get the offset in minutes from UTC. Couple of gotchas with it though.

1. The sign (+/-) of the minutes returned is probably the opposite of what you'd expect. If you are 8 hours behind UTC it will return 480 not -480. See MDN or MSDN for more documentation.
2. It doesn't actually return what timezone the client is reporting it is in like the second example I gave. Just the minutes offset from UTC currently. So it will change based on daylight savings time.

UPDATE 2

While the string splitting examples work they can be confusing to read. Here is a regex version that should be easier to understand and is probably faster (both methods are very fast though).

If you want to know the timezone of the client relative to GMT/UTC here you go:

var gmtRe = /GMT([\-\+]?\d{4})/; // Look for GMT, + or - (optionally), and 4 characters of digits (\d)
var d = new Date().toString();
var tz = gmtRe.exec(d)[1]; // timezone, i.e. -0700

If you'd like the actual name of the timezone try this:

var tzRe = /\(([\w\s]+)\)/; // Look for "(", any words (\w) or spaces (\s), and ")"
var d = new Date().toString();
var tz = tzRe.exec(d)[1]; // timezone, i.e. "Pacific Daylight Time"

In order to get local time in pure Javascript use this built in function

// return new Date().toLocaleTimeString();

See below example

 function getLocaltime(){
   return new Date().toLocaleTimeString();
 }
 console.log(getLocaltime());

Just had to tackle this so thought I would leave my answer. jQuery not required I used to update the element as I already had the object cached.

I first wrote a php function to return the required dates/times to my HTML template

 /**
 * Gets the current location time based on timezone
 * @return string
 */


function get_the_local_time($timezone) {
    
    //$timezone ='Europe/London';
   
    $date = new DateTime('now', new DateTimeZone($timezone));
    
    return array(
        'local-machine-time' => $date->format('Y-m-d\TH:i:s+0000'),
        'local-time' => $date->format('h:i a')
    );
    
}

This is then used in my HTML template to display an initial time, and render the date format required by javascript in a data attribute.

        <span class="box--location__time" data-time="<?php echo $time['local-machine-time']; ?>">
            <?php  echo $time['local-time']; ?>
        </span>

I then used the getUTCHours on my date object to return the time irrespective of the users timezone

> The getUTCHours() method returns the hour (from 0 to 23) of the > specified date and time, according to universal time.

var initClocks = function() {

    var $clocks = $('.box--location__time');

    function formatTime(hours, minutes) {

        if (hours === 0) {
            hours = 12;
        }

        if (hours < 10) {
            hours = "0" + hours;
        }

        if (minutes < 10) {
            minutes = "0" + minutes;
        }

        return {
            hours: hours,
            minutes: minutes
        }
    }

    function displayTime(time, $clockDiv) {

        var currentTime = new Date(time);

        var hours = currentTime.getUTCHours();
        var minutes = currentTime.getUTCMinutes();
        var seconds = currentTime.getUTCSeconds();
        var initSeconds = seconds;

        var displayTime = formatTime(hours, minutes);

        $clockDiv.html(displayTime.hours + ":" + displayTime.minutes + ":" + seconds);

        setInterval(function() {

            if (initSeconds > 60) {
                initSeconds = 1;
            } else {
                initSeconds++;
            }

            currentTime.setSeconds(initSeconds);

            hours = currentTime.getUTCHours();
            minutes = currentTime.getUTCMinutes();
            seconds = currentTime.getUTCSeconds();

            displayTime = formatTime(hours, minutes);

            $clockDiv.html(displayTime.hours + ":" + displayTime.minutes + ":" + seconds);

        }, 1000);

    }



    $clocks.each(function() {

        displayTime($(this).data('time'), $(this));

    });

};

I then use the setSeconds method to update the date object based on the amount of seconds past since page load (simple interval function), and update the HTML

• directly like this :

  new Date((new Date().setHours(new Date().getHours() - (new Date().getTimezoneOffset() / 60)))).toISOString()
  

• more details in this utility function

  function getLocaLTime() {
    // new Date().getTimezoneOffset() : getTimezoneOffset in minutes 
    //for GMT + 1 it is (-60) 
    //for GMT + 2 it is (-120) 
    //..
    let time_zone_offset_in_hours = new Date().getTimezoneOffset() / 60;
    //get current datetime hour
    let current_hour = new Date().getHours();
    //adjust current date hour 
    let local_datetime_in_milliseconds = new Date().setHours(current_hour - time_zone_offset_in_hours);
    //format date in milliseconds to ISO String
    let local_datetime = new Date(local_datetime_in_milliseconds).toISOString();
    return local_datetime;
    }
  

The most reliable way I've found to display the local time of a city or location is by tapping into a Time Zone API such as Google Time Zone API. It returns the correct time zone, and more importantly, Day Light Savings Time offset of any location, which just using JavaScript's Date() object cannot be done as far as I'm aware. There's a good tutorial on using the API to get and display the local time here:

var loc = '35.731252, 139.730291' // Tokyo expressed as lat,lng tuple
var targetDate = new Date() // Current date/time of user computer
var timestamp = targetDate.getTime() / 1000 + targetDate.getTimezoneOffset() * 60 // Current UTC date/time expressed as seconds since midnight, January 1, 1970 UTC
var apikey = 'YOUR_TIMEZONE_API_KEY_HERE'
var apicall = 'https://maps.googleapis.com/maps/api/timezone/json?location=' + loc + '&timestamp=' + timestamp + '&key=' + apikey

var xhr = new XMLHttpRequest() // create new XMLHttpRequest2 object
xhr.open('GET', apicall) // open GET request
xhr.onload = function() {
  if (xhr.status === 200) { // if Ajax request successful
    var output = JSON.parse(xhr.responseText) // convert returned JSON string to JSON object
    console.log(output.status) // log API return status for debugging purposes
    if (output.status == 'OK') { // if API reports everything was returned successfully
      var offsets = output.dstOffset * 1000 + output.rawOffset * 1000 // get DST and time zone offsets in milliseconds
      var localdate = new Date(timestamp * 1000 + offsets) // Date object containing current time of Tokyo (timestamp + dstOffset + rawOffset)
      console.log(localdate.toLocaleString()) // Display current Tokyo date and time
    }
  } else {
    alert('Request failed.  Returned status of ' + xhr.status)
  }
}
xhr.send() // send request

From: Displaying the Local Time of Any City using JavaScript and Google Time Zone API

I found this function is very useful during all of my projects. you can also use it.

getStartTime(){
    let date = new Date();
    var tz = date.toString().split("GMT")[1].split(" (")[0];
    tz = tz.substring(1,5);
    let hOffset = parseInt(tz[0]+tz[1]);
    let mOffset = parseInt(tz[2]+tz[3]);
    let offset = date.getTimezoneOffset() * 60 * 1000;
    let localTime = date.getTime();
    let utcTime = localTime + offset;
    let austratia_brisbane = utcTime + (3600000 * hOffset) + (60000 * mOffset);
    let customDate = new Date(austratia_brisbane);

    let data = {
        day: customDate.getDate(),
        month: customDate.getMonth() + 1,
        year: customDate.getFullYear(),
        hour: customDate.getHours(),
        min: customDate.getMinutes(),
        second: customDate.getSeconds(),
        raw: customDate,
        stringDate: customDate.toString()
    }

    return data;
  }

this will give you the time depending on your time zone.

Thanks.

Here is a version that works well in September 2020 using fetch and https://worldtimeapi.org/api

fetch("https://worldtimeapi.org/api/ip")
  .then(response => response.json())
  .then(data => console.log(data.dst,data.datetime));

I needed to report to the server the local time something happened on the client. (In this specific business case UTC provides no value). I needed to use toIsoString() to have the format compatible with .Net MVC but toIsoString() this always converts it to UTC time (which was being sent to the server).

Inspired by the 'amit saini' answer I now use this

	function toIsoStringInLocalTime(date) {
		return new Date((date.getTime() + (-date.getTimezoneOffset() * 60000))).toISOString()
	}

my code is

function display_c(){
  var refresh=1000; // Refresh rate in milli seconds
  mytime=setTimeout('display_ct()',refresh)
}

  function display_ct() {
  var strcount
  var x = new Date()
  document.getElementById('ct').innerHTML = x;
  tt=display_c();
}

<body onload=display_ct();>
  <span id='ct' ></span>
</body>

You can also make your own nodeJS endpoint, publish it with something like heroku, and access it

require("http").createServer(function (q,r) {
    r.setHeader("accees-control-allow-origin","*")
    r.end(Date.now())
}).listen(process.env.PORT || 80)

Then just access it on JS

fetch ("http://someGerokuApp")
.then(r=>r.text)
. then (r=>console.log(r))

This will still be relative to whatever computer the node app is hosted on, but perhaps you can get the location somehow and provide different endpoints fit the other timezones based on the current one (for example if the server happens to be in California then for a new York timezone just add 1000*60*60*3 milliseconds to Date.now() to add 3 hours)

For simplicity, if it's possible to get the location from the server and send it as a response header, you can just do the calculations for the different time zones in the client side

In fact using heroku they allow you to specify a region that it should be deployed at https://devcenter.heroku.com/articles/regions#specifying-a-region you can use this as reference..

EDIT just realized the timezone is in the date string itself, can just pay the whole thing as a header to be read by the client

require("http").createServer(function (q,r) {
    var d= new Date()
    r.setHeader("accees-control-allow-origin","*")
    r.setHeader("zman", d.toString())
    r.end(d.getTime())
}).listen(process.env.PORT || 80)

Try on this way

    function timenow(){
    var now= new Date(), 
    ampm= 'am', 
    h= now.getHours(), 
    m= now.getMinutes(), 
    s= now.getSeconds();
    if(h>= 12){
        if(h>12) h -= 12;
        ampm= 'pm';
    }

    if(m<10) m= '0'+m;
    if(s<10) s= '0'+s;
    return now.toLocaleDateString()+ ' ' + h + ':' + m + ':' + s + ' ' + ampm;
}

toLocaleDateString()

is a function to change the date time format like toLocaleDateString("en-us")

new Date(Date.now() + (-1*new Date().getTimezoneOffset()*60000)).toISOString()