wp-admin/includes/ms.php:1053Prints JavaScript in the header on the Network Settings screen.
function network_settings_add_js() { ?><script>jQuery( function($) { var languageSelect = $( '#WPLANG' ); $( 'form' ).on( 'submit', function() { /* * Don't show a spinner for English and installed languages, * as there is nothing to download. */ if ( ! languageSelect.find( 'option:selected' ).data( 'installed' ) ) { $( '#submit', this ).after( '<span class="spinner language-install-spinner is-active" />' ); } });} );</script> <?php}Introduced in 4.1.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/ms.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.