javascript php variable

<script type="text/javascript">
   var php_var = "<?php echo $php_var; ?>";
</script>

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

<script>
var p1 = "success";
</script>

<?php
echo "<script>document.writeln(p1);</script>";
?>