how to return php var to extren javascript file\ code example

Example 1: how to use php variable in javascript file

<script type="text/javascript">
// boolean outputs "" if false, "1" if true
var bool = "<?php echo $bool ?>"; 

// numeric value, both with and without quotes
var num = <?php echo $num ?>; // 7
var str_num = "<?php echo $num ?>"; // "7" (a string)

var str = "<?php echo $str ?>"; // "A string here"
</script>

Example 2: how to use php variable in javascript file

<?php
$bool = false;
$num = 3 + 4;
$str = "A string here";
?>