Renaming “Expand Details” within “Add Media”

It’s possible to change the output of the label with jQuery but I’m not sure the best hook to do this besides admin_footer.

// Collapse

var $open = jQuery('.acf-expand-details > .is-open'), 
    $open_icon = $open.find('span');

$open.html('MIN Details -->');
$open.prepend($open_icon);

// Expand

var $close = jQuery('.acf-expand-details > .is-closed'),
    $close_icon = $close.find('span');

$close.html('<-- MAX Details');
$close.prepend($close_icon);

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add_action( 'admin_enqueue_scripts', 'admin_enqueue_scripts_replace_test', 10 );

function admin_enqueue_scripts_replace_test() {
    wp_enqueue_script( 'jquery' );
    add_action( 'admin_footer', 'admin_footer_replace_test', 10 );
}

function admin_footer_replace_test() {
    ?>
    <script>
        jQuery(document).ready(function () {
            // target frame
        });
    </script>
    <?php
}

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You might have to read up on wp.media and take a look at WP Media Javascript Guide for detecting frame events.