resources/src/mediawiki/mediawiki.visibleTimeout.js

   1 ( function ( mw, document ) {
   2         var hidden, visibilityChange,
   3                 nextVisibleTimeoutId = 0,
   4                 activeTimeouts = {},
   5                 init = function ( overrideDoc ) {
   6                         if ( overrideDoc !== undefined ) {
   7                                 document = overrideDoc;
   8                         }
   9
  10                         if ( document.hidden !== undefined ) {
  11                                 hidden = 'hidden';
  12                                 visibilityChange = 'visibilitychange';
  13                         } else if ( document.mozHidden !== undefined ) {
  14                                 hidden = 'mozHidden';
  15                                 visibilityChange = 'mozvisibilitychange';
  16                         } else if ( document.msHidden !== undefined ) {
  17                                 hidden = 'msHidden';
  18                                 visibilityChange = 'msvisibilitychange';
  19                         } else if ( document.webkitHidden !== undefined ) {
  20                                 hidden = 'webkitHidden';
  21                                 visibilityChange = 'webkitvisibilitychange';
  22                         }
  23                 };
  24
  25         init();
  26
  27         /**
  28          * @class mw.visibleTimeout
  29          * @singleton
  30          */
  31         module.exports = {
  32                 /**
  33                  * Generally similar to setTimeout, but turns itself on/off on page
  34                  * visibility changes. The passed function fires after the page has been
  35                  * cumulatively visible for the specified number of ms.
  36                  *
  37                  * @param {Function} fn The action to execute after visible timeout has expired.
  38                  * @param {number} delay The number of ms the page should be visible before
  39                  *  calling fn.
  40                  * @return {number} A positive integer value which identifies the timer. This
  41                  *  value can be passed to clearVisibleTimeout() to cancel the timeout.
  42                  */
  43                 set: function ( fn, delay ) {
  44                         var handleVisibilityChange,
  45                                 timeoutId = null,
  46                                 visibleTimeoutId = nextVisibleTimeoutId++,
  47                                 lastStartedAt = mw.now(),
  48                                 clearVisibleTimeout = function () {
  49                                         if ( timeoutId !== null ) {
  50                                                 clearTimeout( timeoutId );
  51                                                 timeoutId = null;
  52                                         }
  53                                         delete activeTimeouts[ visibleTimeoutId ];
  54                                         if ( hidden !== undefined ) {
  55                                                 document.removeEventListener( visibilityChange, handleVisibilityChange, false );
  56                                         }
  57                                 },
  58                                 onComplete = function () {
  59                                         clearVisibleTimeout();
  60                                         fn();
  61                                 };
  62
  63                         handleVisibilityChange = function () {
  64                                 var now = mw.now();
  65
  66                                 if ( document[ hidden ] ) {
  67                                         // pause timeout if running
  68                                         if ( timeoutId !== null ) {
  69                                                 delay = Math.max( 0, delay - Math.max( 0, now - lastStartedAt ) );
  70                                                 if ( delay === 0 ) {
  71                                                         onComplete();
  72                                                 } else {
  73                                                         clearTimeout( timeoutId );
  74                                                         timeoutId = null;
  75                                                 }
  76                                         }
  77                                 } else {
  78                                         // resume timeout if not running
  79                                         if ( timeoutId === null ) {
  80                                                 lastStartedAt = now;
  81                                                 timeoutId = setTimeout( onComplete, delay );
  82                                         }
  83                                 }
  84                         };
  85
  86                         activeTimeouts[ visibleTimeoutId ] = clearVisibleTimeout;
  87                         if ( hidden !== undefined ) {
  88                                 document.addEventListener( visibilityChange, handleVisibilityChange, false );
  89                         }
  90                         handleVisibilityChange();
  91
  92                         return visibleTimeoutId;
  93                 },
  94
  95                 /**
  96                  * Cancel a visible timeout previously established by calling set.
  97                  * Passing an invalid ID silently does nothing.
  98                  *
  99                  * @param {number} visibleTimeoutId The identifier of the visible
 100                  *  timeout you want to cancel. This ID was returned by the
 101                  *  corresponding call to set().
 102                  */
 103                 clear: function ( visibleTimeoutId ) {
 104                         if ( activeTimeouts.hasOwnProperty( visibleTimeoutId ) ) {
 105                                 activeTimeouts[ visibleTimeoutId ]();
 106                         }
 107                 }
 108         };
 109
 110         if ( window.QUnit ) {
 111                 module.exports.setDocument = init;
 112         }
 113
 114 }( mediaWiki, document ) );