1 files changed, 114 insertions, 0 deletions
diff --git a/www/wiki/resources/src/mediawiki/mediawiki.visibleTimeout.js b/www/wiki/resources/src/mediawiki/mediawiki.visibleTimeout.js
new file mode 100644
index 00000000..e2bbd683
--- /dev/null
+++ b/www/wiki/resources/src/mediawiki/mediawiki.visibleTimeout.js
@@ -0,0 +1,114 @@
+( function ( mw, document ) {
+	var hidden, visibilityChange,
+		nextVisibleTimeoutId = 0,
+		activeTimeouts = {},
+		init = function ( overrideDoc ) {
+			if ( overrideDoc !== undefined ) {
+				document = overrideDoc;
+			}
+
+			if ( document.hidden !== undefined ) {
+				hidden = 'hidden';
+				visibilityChange = 'visibilitychange';
+			} else if ( document.mozHidden !== undefined ) {
+				hidden = 'mozHidden';
+				visibilityChange = 'mozvisibilitychange';
+			} else if ( document.msHidden !== undefined ) {
+				hidden = 'msHidden';
+				visibilityChange = 'msvisibilitychange';
+			} else if ( document.webkitHidden !== undefined ) {
+				hidden = 'webkitHidden';
+				visibilityChange = 'webkitvisibilitychange';
+			}
+		};
+
+	init();
+
+	/**
+	 * @class mw.visibleTimeout
+	 * @singleton
+	 */
+	module.exports = {
+		/**
+		 * Generally similar to setTimeout, but turns itself on/off on page
+		 * visibility changes. The passed function fires after the page has been
+		 * cumulatively visible for the specified number of ms.
+		 *
+		 * @param {Function} fn The action to execute after visible timeout has expired.
+		 * @param {number} delay The number of ms the page should be visible before
+		 *  calling fn.
+		 * @return {number} A positive integer value which identifies the timer. This
+		 *  value can be passed to clearVisibleTimeout() to cancel the timeout.
+		 */
+		set: function ( fn, delay ) {
+			var handleVisibilityChange,
+				timeoutId = null,
+				visibleTimeoutId = nextVisibleTimeoutId++,
+				lastStartedAt = mw.now(),
+				clearVisibleTimeout = function () {
+					if ( timeoutId !== null ) {
+						clearTimeout( timeoutId );
+						timeoutId = null;
+					}
+					delete activeTimeouts[ visibleTimeoutId ];
+					if ( hidden !== undefined ) {
+						document.removeEventListener( visibilityChange, handleVisibilityChange, false );
+					}
+				},
+				onComplete = function () {
+					clearVisibleTimeout();
+					fn();
+				};
+
+			handleVisibilityChange = function () {
+				var now = mw.now();
+
+				if ( document[ hidden ] ) {
+					// pause timeout if running
+					if ( timeoutId !== null ) {
+						delay = Math.max( 0, delay - Math.max( 0, now - lastStartedAt ) );
+						if ( delay === 0 ) {
+							onComplete();
+						} else {
+							clearTimeout( timeoutId );
+							timeoutId = null;
+						}
+					}
+				} else {
+					// resume timeout if not running
+					if ( timeoutId === null ) {
+						lastStartedAt = now;
+						timeoutId = setTimeout( onComplete, delay );
+					}
+				}
+			};
+
+			activeTimeouts[ visibleTimeoutId ] = clearVisibleTimeout;
+			if ( hidden !== undefined ) {
+				document.addEventListener( visibilityChange, handleVisibilityChange, false );
+			}
+			handleVisibilityChange();
+
+			return visibleTimeoutId;
+		},
+
+		/**
+		 * Cancel a visible timeout previously established by calling set.
+		 * Passing an invalid ID silently does nothing.
+		 *
+		 * @param {number} visibleTimeoutId The identifier of the visible
+		 *  timeout you want to cancel. This ID was returned by the
+		 *  corresponding call to set().
+		 */
+		clear: function ( visibleTimeoutId ) {
+			if ( activeTimeouts.hasOwnProperty( visibleTimeoutId ) ) {
+				activeTimeouts[ visibleTimeoutId ]();
+			}
+		}
+	};
+
+	if ( window.QUnit ) {
+		module.exports.setDocument = init;
+	}
+
+}( mediaWiki, document ) );