1 files changed, 68 insertions, 0 deletions
diff --git a/resources/src/mediawiki/mediawiki.confirmCloseWindow.js b/resources/src/mediawiki/mediawiki.confirmCloseWindow.js
new file mode 100644
index 00000000..7fc5c424
--- /dev/null
+++ b/resources/src/mediawiki/mediawiki.confirmCloseWindow.js
@@ -0,0 +1,68 @@
+( function ( mw, $ ) {
+	/**
+	 * @method confirmCloseWindow
+	 * @member mw
+	 *
+	 * Prevent the closing of a window with a confirm message (the onbeforeunload event seems to
+	 * work in most browsers.)
+	 *
+	 * This supersedes any previous onbeforeunload handler. If there was a handler before, it is
+	 * restored when you execute the returned function.
+	 *
+	 *     var allowCloseWindow = mw.confirmCloseWindow();
+	 *     // ... do stuff that can't be interrupted ...
+	 *     allowCloseWindow();
+	 *
+	 * @param {Object} [options]
+	 * @param {string} [options.namespace] Namespace for the event registration
+	 * @param {string} [options.message]
+	 * @param {string} options.message.return The string message to show in the confirm dialog.
+	 * @param {Function} [options.test]
+	 * @param {boolean} [options.test.return=true] Whether to show the dialog to the user.
+	 * @return {Function} Execute this when you want to allow the user to close the window
+	 */
+	mw.confirmCloseWindow = function ( options ) {
+		var savedUnloadHandler,
+			mainEventName = 'beforeunload',
+			showEventName = 'pageshow';
+
+		options = $.extend( {
+			message: mw.message( 'mwe-prevent-close' ).text(),
+			test: function () { return true; }
+		}, options );
+
+		if ( options.namespace ) {
+			mainEventName += '.' + options.namespace;
+			showEventName += '.' + options.namespace;
+		}
+
+		$( window ).on( mainEventName, function () {
+			if ( options.test() ) {
+				// remove the handler while the alert is showing - otherwise breaks caching in Firefox (3?).
+				// but if they continue working on this page, immediately re-register this handler
+				savedUnloadHandler = window.onbeforeunload;
+				window.onbeforeunload = null;
+				setTimeout( function () {
+					window.onbeforeunload = savedUnloadHandler;
+				}, 1 );
+
+				// show an alert with this message
+				if ( $.isFunction( options.message ) ) {
+					return options.message();
+				} else {
+					return options.message;
+				}
+			}
+		} ).on( showEventName, function () {
+			// Re-add onbeforeunload handler
+			if ( !window.onbeforeunload && savedUnloadHandler ) {
+				window.onbeforeunload = savedUnloadHandler;
+			}
+		} );
+
+		// return the function they can use to stop this
+		return function () {
+			$( window ).off( mainEventName + ' ' + showEventName );
+		};
+	};
+} )( mediaWiki, jQuery );