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How to access PHP variables in JavaScript or jQuery rather than <?php echo $variable ?>

Is there any way to get access to a PHP variable in JavaScript?

I have a variable, $a, in PHP and want to get its value in a JavaScript variable.

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closed as exact duplicate by Peter Mortensen, Fluffeh, DCoder, FelipeAls, Donal Fellows Aug 19 at 22:03

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4 Answers

up vote 8 down vote accepted

You can't, you'll have to do something like

<script type="text/javascript">
   var php_var = "<?php echo $php_var; ?>";
</script>

You can also load it with AJAX

rhino is right, the snippet lacks of a type for the sake of brevity.

Also, note that if $php_var has quotes, it will break your script. You shall use addslashes, htmlentities or a custom function.

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rhino is correct, json_encode escapes the variable. – Jonah Nov 26 '10 at 17:51
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W3C states that The type attribute must be specified for each SCRIPT element instance in a document. – stillstanding Nov 26 '10 at 17:51
Right, he was probably just omitting it for the sake of brevity. – Jonah Nov 26 '10 at 17:53
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@stillstanding: Be specific: W3C states where? It's not required in HTML5. – casablanca Nov 26 '10 at 17:54
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@stillstanding: I wouldn't trust W3Schools as much as the actual spec. See w3.org/TR/html5/scripting-1.html#script -- The type attribute gives the language of the script or format of the data. ... The default, which is used if the attribute is absent, is "text/javascript". – casablanca Nov 26 '10 at 18:02
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up vote 5 down vote

metrobalderas is partially right. Partially, because the PHP variable's value may contain some special characters, which are metacharacters in JavaScript. To avoid such problem, use the code below:

<script type="text/javascript">
var something=<?php echo json_encode($a); ?>;
</script>
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+1. Tested, and json_encode does quote and escape strings properly. – Jonah Nov 26 '10 at 18:16
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up vote 0 down vote

I'm not sure how necessary this is, and it adds a call to getElementById, but if you're really keen on getting inline JS out of your code, you can pass it as an HTML attribute, viz:

<span class="metadata" id="metadata-size-of-widget" title="<?php echo json_encode($size_of_widget) ?>"></span>

and then in your JS:

var size_of_widget = document.getElementById("metadata-size-of-widget").title;
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