resources/src/mediawiki.confirmCloseWindow.js

   1 ( function () {
   2         /**
   3          * Prevent the closing of a window with a confirm message (the onbeforeunload event seems to
   4          * work in most browsers.)
   5          *
   6          * This supersedes any previous onbeforeunload handler. If there was a handler before, it is
   7          * restored when you execute the returned release() function.
   8          *
   9          *     var allowCloseWindow = mw.confirmCloseWindow();
  10          *     // ... do stuff that can't be interrupted ...
  11          *     allowCloseWindow.release();
  12          *
  13          * The second function returned is a trigger function to trigger the check and an alert
  14          * window manually, e.g.:
  15          *
  16          *     var allowCloseWindow = mw.confirmCloseWindow();
  17          *     // ... do stuff that can't be interrupted ...
  18          *     if ( allowCloseWindow.trigger() ) {
  19          *         // don't do anything (e.g. destroy the input field)
  20          *     } else {
  21          *         // do whatever you wanted to do
  22          *     }
  23          *
  24          * @method confirmCloseWindow
  25          * @member mw
  26          * @param {Object} [options]
  27          * @param {string} [options.namespace] Namespace for the event registration
  28          * @param {string} [options.message]
  29          * @param {string} options.message.return The string message to show in the confirm dialog.
  30          * @param {Function} [options.test]
  31          * @param {boolean} [options.test.return=true] Whether to show the dialog to the user.
  32          * @return {Object} An object of functions to work with this module
  33          */
  34         mw.confirmCloseWindow = function ( options ) {
  35                 var savedUnloadHandler,
  36                         mainEventName = 'beforeunload',
  37                         showEventName = 'pageshow',
  38                         message;
  39
  40                 options = $.extend( {
  41                         message: mw.message( 'mwe-prevent-close' ).text(),
  42                         test: function () { return true; }
  43                 }, options );
  44
  45                 if ( options.namespace ) {
  46                         mainEventName += '.' + options.namespace;
  47                         showEventName += '.' + options.namespace;
  48                 }
  49
  50                 if ( typeof options.message === 'function' ) {
  51                         message = options.message();
  52                 } else {
  53                         message = options.message;
  54                 }
  55
  56                 $( window ).on( mainEventName, function () {
  57                         if ( options.test() ) {
  58                                 // remove the handler while the alert is showing - otherwise breaks caching in Firefox (3?).
  59                                 // but if they continue working on this page, immediately re-register this handler
  60                                 savedUnloadHandler = window.onbeforeunload;
  61                                 window.onbeforeunload = null;
  62                                 setTimeout( function () {
  63                                         window.onbeforeunload = savedUnloadHandler;
  64                                 }, 1 );
  65
  66                                 // show an alert with this message
  67                                 return message;
  68                         }
  69                 } ).on( showEventName, function () {
  70                         // Re-add onbeforeunload handler
  71                         if ( !window.onbeforeunload && savedUnloadHandler ) {
  72                                 window.onbeforeunload = savedUnloadHandler;
  73                         }
  74                 } );
  75
  76                 /**
  77                  * Return the object with functions to release and manually trigger the confirm alert
  78                  *
  79                  * @ignore
  80                  */
  81                 return {
  82                         /**
  83                          * Remove all event listeners and don't show an alert anymore, if the user wants to leave
  84                          * the page.
  85                          *
  86                          * @ignore
  87                          */
  88                         release: function () {
  89                                 $( window ).off( mainEventName + ' ' + showEventName );
  90                         },
  91                         /**
  92                          * Trigger the module's function manually: Check, if options.test() returns true and show
  93                          * an alert to the user if he/she want to leave this page. Returns false, if options.test() returns
  94                          * false or the user cancelled the alert window (~don't leave the page), true otherwise.
  95                          *
  96                          * @ignore
  97                          * @return {boolean}
  98                          */
  99                         trigger: function () {
 100                                 // use confirm to show the message to the user (if options.text() is true)
 101                                 // eslint-disable-next-line no-alert
 102                                 if ( options.test() && !confirm( message ) ) {
 103                                         // the user want to keep the actual page
 104                                         return false;
 105                                 }
 106                                 // otherwise return true
 107                                 return true;
 108                         }
 109                 };
 110         };
 111 }() );