我们如何在php变量中调用js或jq的变量？

Question

can javascript or jquery variable can be read by php code?

Example

<script>
   var num = 3;
</script>
<php?
   $a = 20;
   $b = num*$a;
?>

anyone?

Answer 1

Short answer - No it can't. But there is an alternative known as AJAX where you can send a javascript variable to a php page and make it accessible to that page. Consider the following example:

$.ajax({
   url:'some-php-page.php',
   type:'post',
   data:{num:3},
   success:function(data_returned)
   {
      // do anything you want with the data returned back
      alert(data_returned); // will alert 60
   }
});

some-php-page.php

$num = $_POST['num']; // the key used in the "data" attribute of the ajax call
$a = 20;
$b = $num*$a;
echo $b;

Of course you'll need to include jQuery library in order to use the $.ajax({}). This can be done through plain javascript too, but I prefer to use jQuery as it is much simpler.