Auto check the "Open link in a new window/tab" checkbox in WordPress

functions.php

<?php
// DO NOT INCLUDE THE OPENING PHP TAG AND INSERT INTO FUNCTIONS.PHP


add_action( 'admin_footer', 'custom_new_link_auto_check', 9999 );
/**
 * Auto check the "Open link in a new window/tab" modal
 */
function custom_new_link_auto_check() { ?>
	<script type="text/javascript">
		jQuery ( function($) {
			$('input#link-target-checkbox').prop('checked', true);
		} );
	</script>
<?php }