php in javascript

1If your whole JavaScript code gets processed by PHP, then you can do it just like that.
2
3If you have individual .js files, and you don't want PHP to process them (for example, for caching reasons), then you can just pass variables around in JavaScript.
4
5For example, in your index.php (or wherever you specify your layout), you'd do something like this:
6
7<script type="text/javascript">
8    var my_var = <?php echo json_encode($my_var); ?>;
9</script>
10You could then use my_var in your JavaScript files.
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12This method also lets you pass other than just simple integer values, as json_encode() also deals with arrays, strings, etc. correctly, serialising them into a format that JavaScript can use.