How do I access PHP variables 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 a better way to do it?
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.
<?php echo $simple; ?> and I think that's right. But you have quotes round <?php echo json_encode($complex); ?> as well, and I think that's wrong --- json_encode() returns valid javascript, so you don't want to quote it, surely?
If AJAX isn't an option you can use nested data structures to simplify.
<?php
$var = array(
'qwe' => 'asd',
'asd' => array(
1 => 2,
3 => 4,
),
'zxc' => 0,
);
?>
<script>var data = <?php echo json_encode($var); ?>;</script>
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.
I ran into a similar issue when building a custom pagination for a site I am working on.
The global variable I created in functions.php was defined and set to 0. I could output this value in my javascript no problem using the method @Karsten outlined above. The issue was with updating the global variable that I initially set to 0 inside the PHP file.
Here is my workaround (hacky? I know!) but after struggling for an hour on a tight deadline the following works:
Inside archive-episodes.php:
<script>
// We define the variable and update it in a php
// function defined in functions.php
var totalPageCount;
</script>
Inside functions.php
<?php
$totalPageCount = WP_Query->max_num_pages; // In my testing scenario this number is 8.
echo '<script>totalPageCount = $totalPageCount;</script>';
?>
To keep it simple, I was outputting the totalPageCount variable in an $ajax.success callback via alert.
$.ajax({
url: ajaxurl,
type: 'POST',
data: {"action": "infinite_scroll", "page_no": pageNumber, "posts_per_page": numResults},
beforeSend: function() {
$(".ajaxLoading").show();
},
success: function(data) {
//alert("DONE LOADING EPISODES");
$(".ajaxLoading").hide();
var $container = $("#episode-container");
if(firstRun) {
$container.prepend(data);
initMasonry($container);
ieMasonryFix();
initSearch();
} else {
var $newItems = $(data);
$container.append( $newItems ).isotope( 'appended', $newItems );
}
firstRun = false;
addHoverState();
smartResize();
alert(totalEpiPageCount); // THIS OUTPUTS THE CORRECT PAGE TOTAL
}
Be it as it may, I hope this helps others! If anyone has a "less-hacky" version or best-practise example I'm all ears.
Basically, yes. You write alert('<?php echo($phpvariable); ?>');
There are sure other ways to interoperate, but none of which i can think of being as simple (or better) as the above.
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.
