I have a third party script which is
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After your clarified in a comment
Yeah, including javascript will apply pagewide if nothing else is specified in the javascript.
You need to do something like:
<div class="post <%= 'copyright' if post.copyright%>">
<img src="somesrc.jpg"></img>
</div>
and then apply the javascript only to the css selector 'div.copyright img'. Something along the lines of that. Depends on what the javascript supports or if you can change the source.