Update a PHP variable within a Javascript function

Question

I am using the following code to display the current server time:

<p id="demo"></p>
<script>
  function segundoAtual() {
    var n = <?php
	date_default_timezone_set('America/Sao_Paulo');
	$cH = date('G');
	$cM = date('i');
	$cS = date('s');
	echo ($cH*60*60)+($cM*60)+$cS;
	?>;
    	var segundosInicio = inicioYujiaLynxA+(-difLynx);

c = (( n - segundosInicio + duraYujia ) % duraYujia ) / duraYujia;

i = Math.floor((mapYujia.length * 2 - 2) * c);
if( i >= mapYujia.length ) i = mapYujia.length * 2 - i - 1;

var pin = document.getElementById('pin');
pin.style.left = (mapYujia[i][0]/600*100) + '%';
pin.style.top  = (mapYujia[i][1]/757*100) + '%';
  }
    segundoAtual();
    setInterval(segundoAtual, 1);
</script>

The variables segundosInicio, inicioYujiaLynxA and difLynx are defined in another file, called through <script src="servers.js"></script> at the beginning of the document.

The variable segundoAtual defines the position of an element (pin) on a map...

The result is obtained in seconds from midnight tonight.

Either setInterval is not running to update the time, or the variable can only be updated if the page is reloaded?

Answer 1

Only when the page is updated, ideally would you do the following:

Create a PHP page that returns the server time. Create a second page with your javascript by calling via ajax that page that returns the time. So you can update your javascript element.

test php.

<script   src="https://code.jquery.com/jquery-3.1.1.min.js"   integrity="sha256-hVVnYaiADRTO2PzUGmuLJr8BLUSjGIZsDYGmIJLv2b8="   crossorigin="anonymous"></script>
<p id="demo"></p>
<script>
$( document ).ready(function() {
  // Handler for .ready() called.
        update();
});
function update(){
setInterval(
    function() {

$.ajax({
    url: "hora.php",
    success: function(n){
  document.getElementById("demo").innerHTML = n;
    segundoAtual(parseInt(n))
    }
});

    },

1000);
}

    function segundoAtual(n) {

        var segundosInicio = inicioYujiaLynxA+(-difLynx);

c = (( n - segundosInicio + duraYujia ) % duraYujia ) / duraYujia;

i = Math.floor((mapYujia.length * 2 - 2) * c);
if( i >= mapYujia.length ) i = mapYujia.length * 2 - i - 1;

var pin = document.getElementById('pin');
pin.style.left = (mapYujia[i][0]/600*100) + '%';
pin.style.top  = (mapYujia[i][1]/757*100) + '%';
  }

</script>

php time.

<?php
date_default_timezone_set('America/Sao_Paulo');
$cH = date('G');
$cM = date('i');
$cS = date('s');
echo ($cH*60*60)+($cM*60)+$cS;
?>