How to access php variables in Javascipt or Jquery rather than <?php echo $variable ?>

Question

How to access PHP varibles in Javascript or Jquery? Do I have to write

<?php echo $variable1 ?>
<?php echo $variable2 ?>
<?php echo $variable3 ?>
...
<?php echo $variablen ?>

I know I can store some variables in cookies,and access these values via cookies, but values in cookies are relatively stable values, moreover, there is a limit, you can not store many values in cookies, and the method is not that convenient. Is there other better way to do it?

Answer 1

Basically, yes. You write alert('<?php echo($phpvariable); ?>');

There are sure other ways to interoperate, but none of which i can think of being as simple (or better) as the above.

Answer 2

I would say echo() ing them directly into the Javascript source code is the most reliable and downward compatible way. Stay with that unless you have a good reason not to.

Answer 3

You're asking kind of a two-part question. As far as syntax (I think since PHP4?) you can use:

<?=$var?>

... if PHP is configured to allow it. And it is on most servers.

As far as storing user data, you also have the option of storing it in the session:

$_SESSION['bla'] = "so-and-so";

for persistence from page to page. You could also of course use a database. You can even have PHP store the session variables in the db. It just depends on what you need.

Answer 4

Your example shows the most simple way of passing php variables to javascript. You can also use json_encode for more complex things like arrays:

<?php
$simple = 'simple string';
$complex = array('more', 'complex', 'object', array('foo', 'bar'));
?>
<script type="text/javascript">
var simple = '<?php echo $simple; ?>';
var complex = <?php echo json_encode($complex); ?>;
</script>

Other than that, if you really want to "interact" between php and javascript you should use ajax.

Using cookies for this is a very unsafe and unreliable way, as they are stored clientside and therefore open for any manipulation or won't even get accepted/saved. Don't use them for this type of interaction. jQuery.ajax is a good start imho.

Answer 5

If AJAX isn't an option you can use nested data structures to simplify.

<?php
$var = array(
  'qwe' => 'asd',
  'asd' => array(
    1 => 2,
    3 => 4,
    )
  'zxc' => 0,
  ); ?>
var data = <?php echo json_encode($var); ?>;