Running script based on Category

I have a child theme with function.php where I am running a script in the header but now I want to tweak it to run only on posts listed under one category and avoid on homepage or other categories. Here is my existing code which I modified but it is firing the script on the entire website.

add_action('wp_head', 'mailchimp_wp_head');
function mailchimp_wp_head() {
    ?>
        <?php if ( is_category( 93 ) ) :?> 
        <script id="mcjs">!function(c,h,i,m,p){m=c.createElement(h),p=c.getElementsByTagName(h)[0],m.async=1,m.src=i,p.parentNode.insertBefore(m,p)}(document,"script","https://chimpstatic.com/mcjs-connected/js/users/hidden.js");</script>
        <?php endif; ?>
    <?php
}

Thanks!

Answers:

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Method 1

run only on posts listed under one category

I highlighted that “posts” because if so, then the conditional tag you should use is in_category() and not is_category() which is for category archive pages (e.g. example.com/category/foo) — so for example, is_category( 93 ) checks if the current archive page is for the category (with the ID of) 93, whereas in_category( 93 ) checks if the current post is in the category 93.

So try with:

<?php if ( is_single() && in_category( 93 ) ) :?> 
<script id="mcjs">!function(c,h,i,m,p){m=c.createElement(h),p=c.getElementsByTagName(h)[0],m.async=1,m.src=i,p.parentNode.insertBefore(m,p)}(document,"script","https://chimpstatic.com/mcjs-connected/js/users/hidden.js");</script>
<?php endif; ?>

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