exchange data between php and javascript code example

Example 1: php pass a variabele to js

<script>
'var name = <?php echo json_encode($name); ?>;
</script>'

Example 2: how to use php echo data in javascript

<?php
$php_variable = 'string'; //Define our PHP variable. You can of course get the value of this variable however you need.
?>			
        <script> js_variable_name = "<?php echo $php_variable; ?>";</script>