wp-admin/includes/options.php:113Display JavaScript on the page.
function options_reading_add_js() { ?><script> jQuery( function($) { var section = $('#front-static-pages'), staticPage = section.find('input:radio[value="page"]'), selects = section.find('select'), check_disabled = function(){ selects.prop( 'disabled', ! staticPage.prop('checked') ); }; check_disabled(); section.find( 'input:radio' ).on( 'change', check_disabled ); } );</script> <?php}Introduced in 3.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-admin/includes/options.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.