Note: After saving, you have to bypass your browser's cache to see the changes. Google Chrome, Firefox, Microsoft Edge and Safari: Hold down the ⇧ Shift key and click the Reload toolbar button. For details and instructions about other browsers, see Wikipedia:Bypass your cache.
/**
 * Based on: [[:zh:MediaWiki:Gadget-T210739.js]] by Xiplus
 * Gadget version: [[User:JJMC89/Gadget-T210739.js]]
 */

$.when( $.ready, mw.loader.using( ['oojs-ui', 'mediawiki.api'] ) ).then( function() {

	if (document.getElementsByName("wpDeleteAndMove").length < 1) {
		return;
	}
	
	var msg_button_label = 'Delete the destination page';
	var msg_button_title = 'Use the API to delete the destination page';
	var msg_delete_reason = '[[WP:G6|G6]]: Deleted to make way for move';
	var msg_delete_success = 'Successfully deleted ';
	var msg_delete_fail = 'An error occurred while deleting:';
	
	var button = new OO.ui.ButtonWidget( {
		flags: [ 'primary', 'destructive' ],
	    label: msg_button_label,
	    icon: 'trash',
	    title: msg_button_title
	} ).on('click', function () {
		var target = mw.config.get('wgFormattedNamespaces')[document.getElementsByName('wpNewTitleNs')[0].value];
		if (target !== '') {
			target += ':';
		}
		target += document.getElementsByName('wpNewTitleMain')[0].value;
	
	    new mw.Api().postWithEditToken({
	        action: 'delete',
	        title: target,
	        reason: msg_delete_reason
	    }).then(function(e) {
	        mw.notify(msg_delete_success +  target);
	    }, function(e) {
	        mw.notify(msg_delete_fail + e);
	    });
	});
	$(document.getElementsByName('wpMove')[0].parentElement.parentElement).append( button.$element );
	
} );