Answers for "how to use php variable in js"

javascript php variable

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

js var to php

<script>
   var res = "success";
</script>
<?php
   echo "<script>document.writeln(res);</script>";
?>

how to get a variable from php to javascript

<script>
   var res = "success";
</script>
<?php
   echo "<script>document.writeln(res);</script>";
?>