lib/dojo/_base/unload.js.uncompressed.js

   1 define("dojo/_base/unload", ["./kernel", "./lang", "../on"], function(dojo, lang, on){
   2
   3 // module:
   4 //              dojo/unload
   5
   6 var win = window;
   7
   8 var unload = {
   9         // summary:
  10         //              This module contains the document and window unload detection API.
  11
  12         addOnWindowUnload: function(/*Object|Function?*/ obj, /*String|Function?*/ functionName){
  13                 // summary:
  14                 //              registers a function to be triggered when window.onunload
  15                 //              fires.
  16                 // description:
  17                 //              The first time that addOnWindowUnload is called Dojo
  18                 //              will register a page listener to trigger your unload
  19                 //              handler with. Note that registering these handlers may
  20                 //              destroy "fastback" page caching in browsers that support
  21                 //              it. Be careful trying to modify the DOM or access
  22                 //              JavaScript properties during this phase of page unloading:
  23                 //              they may not always be available. Consider
  24                 //              addOnUnload() if you need to modify the DOM or do
  25                 //              heavy JavaScript work since it fires at the equivalent of
  26                 //              the page's "onbeforeunload" event.
  27                 // example:
  28                 //      |       unload.addOnWindowUnload(functionPointer)
  29                 //      |       unload.addOnWindowUnload(object, "functionName");
  30                 //      |       unload.addOnWindowUnload(object, function(){ /* ... */});
  31
  32                 if (!dojo.windowUnloaded){
  33                         on(win, "unload", (dojo.windowUnloaded = function(){
  34                                 // summary:
  35                                 //              signal fired by impending window destruction. You may use
  36                                 //              dojo.addOnWindowUnload() to register a listener for this
  37                                 //              event. NOTE: if you wish to dojo.connect() to this method
  38                                 //              to perform page/application cleanup, be aware that this
  39                                 //              event WILL NOT fire if no handler has been registered with
  40                                 //              addOnWindowUnload(). This behavior started in Dojo 1.3.
  41                                 //              Previous versions always triggered windowUnloaded(). See
  42                                 //              addOnWindowUnload for more info.
  43                         }));
  44                 }
  45                 on(win, "unload", lang.hitch(obj, functionName));
  46         },
  47
  48         addOnUnload: function(/*Object?|Function?*/ obj, /*String|Function?*/ functionName){
  49                 // summary:
  50                 //              registers a function to be triggered when the page unloads.
  51                 // description:
  52                 //              The first time that addOnUnload is called Dojo will
  53                 //              register a page listener to trigger your unload handler
  54                 //              with.
  55                 //
  56                 //              In a browser environment, the functions will be triggered
  57                 //              during the window.onbeforeunload event. Be careful of doing
  58                 //              too much work in an unload handler. onbeforeunload can be
  59                 //              triggered if a link to download a file is clicked, or if
  60                 //              the link is a javascript: link. In these cases, the
  61                 //              onbeforeunload event fires, but the document is not
  62                 //              actually destroyed. So be careful about doing destructive
  63                 //              operations in a dojo.addOnUnload callback.
  64                 //
  65                 //              Further note that calling dojo.addOnUnload will prevent
  66                 //              browsers from using a "fast back" cache to make page
  67                 //              loading via back button instantaneous.
  68                 // example:
  69                 //      |       dojo.addOnUnload(functionPointer)
  70                 //      |       dojo.addOnUnload(object, "functionName")
  71                 //      |       dojo.addOnUnload(object, function(){ /* ... */});
  72
  73                 on(win, "beforeunload", lang.hitch(obj, functionName));
  74         }
  75 };
  76
  77 dojo.addOnWindowUnload = unload.addOnWindowUnload;
  78 dojo.addOnUnload = unload.addOnUnload;
  79
  80 return unload;
  81
  82 });