Including PHP variables in an external JS file?

Question

I have a few lines of jQuery in my web application. This code is inline at the moment because it accepts a couple of PHP variables.

<script type="text/javascript">

$(document).ready(function(){

    $('.post<?php echo $post->id; ?>').click(function() {

        $.ajax({

            type: 'POST',
            url: 'http://domain.com/ajax/add_love',
            data: { 
                post_id: <?php echo $post->id; ?>,
                user_id: <?php echo $active_user->id; ?>,
                <?php echo $token; ?>: '<?php echo $hash; ?>'

            },
            dataType: 'json',
            success: function(response) {

                $('.post<?php echo $post->id; ?>').html(response.total_loves).toggleClass('loved');

            }

        });

        return false;

    });

});

</script>

I'm a big fan of best practices though, so I would like to move my jQuery into an external JS file.

How could I achieve such a feat?

Any tips? I'm still relatively new to jQuery and PHP.

Thanks!

:)

Answer 1

My solution combines several techniques, some of which are already mentioned within the answers to this question.

Yes, separate PHP from JS

First of all: yes, you should separate your JS from PHP. You can put it in a separate file, but you will need to make some changes into your current code. Do not make JS file dynamically generated - it actually kills the advantages of separating JS code into separate file (you cannot cache it etc.).

Common variables as global variables / function arguments

Next, store your common variables as global variables in the header of HTML file (you do not really have much choice, although there are other alternatives), preferably grouped in one object:

var Globals = <?php echo json_encode(array(
    'active_user_id' => $active_user->id,
    'token' => $token,
    'hash' => $hash,
)); ?>;

Alternatively you can pass all of them as argument(s) to the function you will call, but I assumed you are using them also in other places in your script.

Container-dependent data stored in data- attributes

Then use data- attributes for storing real data associated with containers. You won't need post1/post2/post3-like classes and separate event handlers for them:

<div data-post-id="10">here is something</div>

instead of eg.:

<div class="post10">here is something</div>

How to read globals and data- attributes from external JS file

And then your JavaScript may look like:

$(document).ready(function(){
    $('[data-post-id]').click(function() {
        var el = $(this);
        var data = { 
            'post_id': el.data('post-id'),
            'user_id': Globals.active_user_id
        };
        data[Globals.token] = Globals.hash;
        $.ajax({
            'type': 'POST',
            'url': 'http://domain.com/ajax/add_love',
            'data': data,
            'dataType': 'json',
            'success': function(response) {
                el.html(response.total_loves).toggleClass('loved');
            }
        });
        return false;
    });
});

And this should be sufficient (although I did not test it).

Answer 2

You could always call the function with parameters from PHP:

somefile.js:

function func(params) {
    //params is now from PHP
    //params.foo == "bar"
}

somefile.php:

<?php
    $params = array('foo' => 'bar');
?>

<script type="text/javascript">
$(function() {
    func(<?php echo json_encode($params); ?>);
});
</script>

I tend to go with this approach because it avoids global variables while allowing easily transporting variables.

I like to use json_encode also because anything valid JSON is valid JS meaning you don't have to worry about escaping ' or " if you use a string and echo PHP inside of it.