assign php value to js variable code example

Example 1: javascript access php variable

//passing PHP variable to JavaScript
var myJSVar = <?php echo json_encode($myPHPVar); ?>;

Example 2: how to assign value of a js variable to a php variable

<script> document.cookie = "myJavascriptVar = " + myJavascriptVar </script>
<?php
     $myPhpVar= $_COOKIE['myJavascriptVar'];
?>