Load javascript only when specify.

This is only for prettyPhoto. Only for content that have “rel=’prettyPhoto'” inside.

Have you tried using the template_redirect hook instead of wp_print_scripts?

I’m not sure but this hook works only for templates that I choose. If I add rel=prettyPhoto to images that not belong to my templates this script doesn’t load. This is not universal. If I’m not right please explain how this hook work.
I found this snippet, but nothing.

If the hooks doesn’t work, you could just do the if statement in your footer.php after wp_footer().

<?php if ((is_single() || is_page()) && (strpos($post->post_content, 'rel="prettyPhoto"') > 1)) { ?>
<script type="text/javascript" src="<?php bloginfo('template_directory'); ?>/js/jquery.prettyPhoto.js"></script>
<?php } ?>

Nothing! I don’t know why this doesn’t work for me. Is there any way to check what return this function, e.g. print_r? Another way to do this and nothing for me.

Try checking $wp_scripts global variable.

So doing a simple if statement in the footer doesn’t work? Did you copy paste exactly what I posted because I just noticed you have /includes/ in one of the code you’ve posted?

If doing the if statement without using wp_enqueue_script doesn’t work then that would suggest the condition is wrong.

I copy/paste your code and add /includes/. I check my code before save.

Then that means there’s something wrong with your if statement condition.

You wrote

Only for content that have “rel=’prettyPhoto'” inside.

but you using double quotes "prettyPhoto" in the code?

I’m checking global variable $wp_scripts and they show all scripts that my blog have and prettyPhoto is not present.

No, in code I have 'rel="prettyPhoto"', in template I have rel="prettyPhoto". Quotes the same.

Well, like I’ve said, if using the following code after wp_footer(); in footer.php (not in a function) doesn’t work then it means your condition is wrong.

<?php if ((is_single() || is_page()) && (strpos($post->post_content, 'rel="prettyPhoto"') > 1)) { ?>
<script type="text/javascript" src="<?php bloginfo('template_directory'); ?>/includes/js/jquery.prettyPhoto.js"></script>
<?php } ?>

I don’t use prettyphoto so I changed 'rel="prettyPhoto"' to something else and tried it on my test blog. It works fine. The js code is displaying in the source code of the desired page.

It’s to complicated. I have the same code like you past. I don’t know whats wrong.((

I had assume your condition was correct from the start so it’s never crossed my mind but I’m pretty sure the reason it’s not working is because rel="prettyPhoto" doesn’t exist in post_content. The plugin should be adding it in through the_content filter everytime the page generates.

Does the plugin add rel="prettyPhoto" to every <img> tag? If so, you can just check for <img> tags with strpos($post->post_content, '<img') !== false

No, only for some images, not for all.

Ok, try this:

function my_prettyphoto_script($content) {
	if ((is_single() || is_page()) && (strpos($content, 'rel="prettyPhoto') > 1)) {
		wp_enqueue_script( 'prettyPhotojs', get_bloginfo('template_directory').'/includes/js/jquery.prettyPhoto.js', array( 'jquery' ), '', true );
	}
	return $content;
}
add_filter('the_content', 'my_prettyphoto_script', 100, 1);

Adding a condition to enqueue prettyphoto script after the rels have been added through the_content filter.

Edit: I’ve tried the plugin and I left out the closing double quote in 'rel="prettyphoto' because it adds the post ID after it.