wp-admin\admin-header.php
74:var ajaxurl = '<?php echo admin_url( 'admin-ajax.php', 'relative' ); ?>',

wp-admin\customize.php
93:var ajaxurl = <?php echo wp_json_encode( admin_url( 'admin-ajax.php', 'relative' ) ); ?>;

wp-admin\includes\class-wp-press-this.php
1267:           var ajaxurl = '<?php echo esc_js( admin_url( 'admin-ajax.php', 'relative' ) ); ?>',

wp-admin\includes\media.php
463:var ajaxurl = '<?php echo admin_url( 'admin-ajax.php', 'relative' ); ?>', pagenow = 'media-upload-popup', adminpage = 'media-upload-popup',

wp-admin\includes\template.php
1585:var ajaxurl = '<?php echo admin_url( 'admin-ajax.php', 'relative' ); ?>',

wp-includes\class-wp-editor.php
1239:                   echo 'var ajaxurl = "' . admin_url( 'admin-ajax.php', 'relative' ) . '";';

wp-includes\general-template.php
3469:           $settings['ajaxurl'] = admin_url( 'admin-ajax.php', 'relative' );

wp-includes\script-loader.php
462:                    'ajaxurl' => admin_url( 'admin-ajax.php', 'relative' ),