PHP

using js variable in php

<script type="text/javascript">
var abc= 'this is text';
<?php $abc = "<script>document.write(abc)</script>"?>   
</script>
<?php echo $abc;?>

how to assign value of a js variable to a php variable

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

How can I use a JavaScript variable as a PHP variable?

<script type="text/javascript">
var jvalue = 'this is javascript value';

<?php $abc = "<script>document.write(jvalue)</script>"?>   
</script>
<?php echo  'php_'.$abc;?>