Adding upstream version 6.4.3+dfsg1.upstream/6.4.3+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 906 insertions, 0 deletions

diff --git a/wp-includes/js/heartbeat.js b/wp-includes/js/heartbeat.js
new file mode 100644
index 0000000..f3a92b0
--- /dev/null
+++ b/wp-includes/js/heartbeat.js
@@ -0,0 +1,906 @@
+/**
+ * Heartbeat API
+ *
+ * Heartbeat is a simple server polling API that sends XHR requests to
+ * the server every 15 - 60 seconds and triggers events (or callbacks) upon
+ * receiving data. Currently these 'ticks' handle transports for post locking,
+ * login-expiration warnings, autosave, and related tasks while a user is logged in.
+ *
+ * Available PHP filters (in ajax-actions.php):
+ * - heartbeat_received
+ * - heartbeat_send
+ * - heartbeat_tick
+ * - heartbeat_nopriv_received
+ * - heartbeat_nopriv_send
+ * - heartbeat_nopriv_tick
+ * @see wp_ajax_nopriv_heartbeat(), wp_ajax_heartbeat()
+ *
+ * Custom jQuery events:
+ * - heartbeat-send
+ * - heartbeat-tick
+ * - heartbeat-error
+ * - heartbeat-connection-lost
+ * - heartbeat-connection-restored
+ * - heartbeat-nonces-expired
+ *
+ * @since 3.6.0
+ * @output wp-includes/js/heartbeat.js
+ */
+
+( function( $, window, undefined ) {
+
+	/**
+	 * Constructs the Heartbeat API.
+	 *
+	 * @since 3.6.0
+	 *
+	 * @return {Object} An instance of the Heartbeat class.
+	 * @constructor
+	 */
+	var Heartbeat = function() {
+		var $document = $(document),
+			settings = {
+				// Suspend/resume.
+				suspend: false,
+
+				// Whether suspending is enabled.
+				suspendEnabled: true,
+
+				// Current screen id, defaults to the JS global 'pagenow' when present
+				// (in the admin) or 'front'.
+				screenId: '',
+
+				// XHR request URL, defaults to the JS global 'ajaxurl' when present.
+				url: '',
+
+				// Timestamp, start of the last connection request.
+				lastTick: 0,
+
+				// Container for the enqueued items.
+				queue: {},
+
+				// Connect interval (in seconds).
+				mainInterval: 60,
+
+				// Used when the interval is set to 5 seconds temporarily.
+				tempInterval: 0,
+
+				// Used when the interval is reset.
+				originalInterval: 0,
+
+				// Used to limit the number of Ajax requests.
+				minimalInterval: 0,
+
+				// Used together with tempInterval.
+				countdown: 0,
+
+				// Whether a connection is currently in progress.
+				connecting: false,
+
+				// Whether a connection error occurred.
+				connectionError: false,
+
+				// Used to track non-critical errors.
+				errorcount: 0,
+
+				// Whether at least one connection has been completed successfully.
+				hasConnected: false,
+
+				// Whether the current browser window is in focus and the user is active.
+				hasFocus: true,
+
+				// Timestamp, last time the user was active. Checked every 30 seconds.
+				userActivity: 0,
+
+				// Flag whether events tracking user activity were set.
+				userActivityEvents: false,
+
+				// Timer that keeps track of how long a user has focus.
+				checkFocusTimer: 0,
+
+				// Timer that keeps track of how long needs to be waited before connecting to
+				// the server again.
+				beatTimer: 0
+			};
+
+		/**
+		 * Sets local variables and events, then starts the heartbeat.
+		 *
+		 * @since 3.8.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function initialize() {
+			var options, hidden, visibilityState, visibilitychange;
+
+			if ( typeof window.pagenow === 'string' ) {
+				settings.screenId = window.pagenow;
+			}
+
+			if ( typeof window.ajaxurl === 'string' ) {
+				settings.url = window.ajaxurl;
+			}
+
+			// Pull in options passed from PHP.
+			if ( typeof window.heartbeatSettings === 'object' ) {
+				options = window.heartbeatSettings;
+
+				// The XHR URL can be passed as option when window.ajaxurl is not set.
+				if ( ! settings.url && options.ajaxurl ) {
+					settings.url = options.ajaxurl;
+				}
+
+				/*
+				 * The interval can be from 15 to 120 seconds and can be set temporarily to 5 seconds.
+				 * It can be set in the initial options or changed later through JS and/or through PHP.
+				 */
+				if ( options.interval ) {
+					settings.mainInterval = options.interval;
+
+					if ( settings.mainInterval < 15 ) {
+						settings.mainInterval = 15;
+					} else if ( settings.mainInterval > 120 ) {
+						settings.mainInterval = 120;
+					}
+				}
+
+				/*
+				 * Used to limit the number of Ajax requests. Overrides all other intervals
+				 * if they are shorter. Needed for some hosts that cannot handle frequent requests
+				 * and the user may exceed the allocated server CPU time, etc. The minimal interval
+				 * can be up to 600 seconds, however setting it to longer than 120 seconds
+				 * will limit or disable some of the functionality (like post locks).
+				 * Once set at initialization, minimalInterval cannot be changed/overridden.
+				 */
+				if ( options.minimalInterval ) {
+					options.minimalInterval = parseInt( options.minimalInterval, 10 );
+					settings.minimalInterval = options.minimalInterval > 0 && options.minimalInterval <= 600 ? options.minimalInterval : 0;
+				}
+
+				if ( settings.minimalInterval && settings.mainInterval < settings.minimalInterval ) {
+					settings.mainInterval = settings.minimalInterval;
+				}
+
+				// 'screenId' can be added from settings on the front end where the JS global
+				// 'pagenow' is not set.
+				if ( ! settings.screenId ) {
+					settings.screenId = options.screenId || 'front';
+				}
+
+				if ( options.suspension === 'disable' ) {
+					settings.suspendEnabled = false;
+				}
+			}
+
+			// Convert to milliseconds.
+			settings.mainInterval = settings.mainInterval * 1000;
+			settings.originalInterval = settings.mainInterval;
+			if ( settings.minimalInterval ) {
+				settings.minimalInterval = settings.minimalInterval * 1000;
+			}
+
+			/*
+			 * Switch the interval to 120 seconds by using the Page Visibility API.
+			 * If the browser doesn't support it (Safari < 7, Android < 4.4, IE < 10), the
+			 * interval will be increased to 120 seconds after 5 minutes of mouse and keyboard
+			 * inactivity.
+			 */
+			if ( typeof document.hidden !== 'undefined' ) {
+				hidden = 'hidden';
+				visibilitychange = 'visibilitychange';
+				visibilityState = 'visibilityState';
+			} else if ( typeof document.msHidden !== 'undefined' ) { // IE10.
+				hidden = 'msHidden';
+				visibilitychange = 'msvisibilitychange';
+				visibilityState = 'msVisibilityState';
+			} else if ( typeof document.webkitHidden !== 'undefined' ) { // Android.
+				hidden = 'webkitHidden';
+				visibilitychange = 'webkitvisibilitychange';
+				visibilityState = 'webkitVisibilityState';
+			}
+
+			if ( hidden ) {
+				if ( document[hidden] ) {
+					settings.hasFocus = false;
+				}
+
+				$document.on( visibilitychange + '.wp-heartbeat', function() {
+					if ( document[visibilityState] === 'hidden' ) {
+						blurred();
+						window.clearInterval( settings.checkFocusTimer );
+					} else {
+						focused();
+						if ( document.hasFocus ) {
+							settings.checkFocusTimer = window.setInterval( checkFocus, 10000 );
+						}
+					}
+				});
+			}
+
+			// Use document.hasFocus() if available.
+			if ( document.hasFocus ) {
+				settings.checkFocusTimer = window.setInterval( checkFocus, 10000 );
+			}
+
+			$(window).on( 'pagehide.wp-heartbeat', function() {
+				// Don't connect anymore.
+				suspend();
+
+				// Abort the last request if not completed.
+				if ( settings.xhr && settings.xhr.readyState !== 4 ) {
+					settings.xhr.abort();
+				}
+			});
+
+			$(window).on(
+				'pageshow.wp-heartbeat',
+				/**
+				 * Handles pageshow event, specifically when page navigation is restored from back/forward cache.
+				 *
+				 * @param {jQuery.Event} event
+				 * @param {PageTransitionEvent} event.originalEvent
+				 */
+				function ( event ) {
+					if ( event.originalEvent.persisted ) {
+						/*
+						 * When page navigation is stored via bfcache (Back/Forward Cache), consider this the same as
+						 * if the user had just switched to the tab since the behavior is similar.
+						 */
+						focused();
+					}
+				}
+			);
+
+			// Check for user activity every 30 seconds.
+			window.setInterval( checkUserActivity, 30000 );
+
+			// Start one tick after DOM ready.
+			$( function() {
+				settings.lastTick = time();
+				scheduleNextTick();
+			});
+		}
+
+		/**
+		 * Returns the current time according to the browser.
+		 *
+		 * @since 3.6.0
+		 * @access private
+		 *
+		 * @return {number} Returns the current time.
+		 */
+		function time() {
+			return (new Date()).getTime();
+		}
+
+		/**
+		 * Checks if the iframe is from the same origin.
+		 *
+		 * @since 3.6.0
+		 * @access private
+		 *
+		 * @return {boolean} Returns whether or not the iframe is from the same origin.
+		 */
+		function isLocalFrame( frame ) {
+			var origin, src = frame.src;
+
+			/*
+			 * Need to compare strings as WebKit doesn't throw JS errors when iframes have
+			 * different origin. It throws uncatchable exceptions.
+			 */
+			if ( src && /^https?:\/\//.test( src ) ) {
+				origin = window.location.origin ? window.location.origin : window.location.protocol + '//' + window.location.host;
+
+				if ( src.indexOf( origin ) !== 0 ) {
+					return false;
+				}
+			}
+
+			try {
+				if ( frame.contentWindow.document ) {
+					return true;
+				}
+			} catch(e) {}
+
+			return false;
+		}
+
+		/**
+		 * Checks if the document's focus has changed.
+		 *
+		 * @since 4.1.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function checkFocus() {
+			if ( settings.hasFocus && ! document.hasFocus() ) {
+				blurred();
+			} else if ( ! settings.hasFocus && document.hasFocus() ) {
+				focused();
+			}
+		}
+
+		/**
+		 * Sets error state and fires an event on XHR errors or timeout.
+		 *
+		 * @since 3.8.0
+		 * @access private
+		 *
+		 * @param {string} error  The error type passed from the XHR.
+		 * @param {number} status The HTTP status code passed from jqXHR
+		 *                        (200, 404, 500, etc.).
+		 *
+		 * @return {void}
+		 */
+		function setErrorState( error, status ) {
+			var trigger;
+
+			if ( error ) {
+				switch ( error ) {
+					case 'abort':
+						// Do nothing.
+						break;
+					case 'timeout':
+						// No response for 30 seconds.
+						trigger = true;
+						break;
+					case 'error':
+						if ( 503 === status && settings.hasConnected ) {
+							trigger = true;
+							break;
+						}
+						/* falls through */
+					case 'parsererror':
+					case 'empty':
+					case 'unknown':
+						settings.errorcount++;
+
+						if ( settings.errorcount > 2 && settings.hasConnected ) {
+							trigger = true;
+						}
+
+						break;
+				}
+
+				if ( trigger && ! hasConnectionError() ) {
+					settings.connectionError = true;
+					$document.trigger( 'heartbeat-connection-lost', [error, status] );
+					wp.hooks.doAction( 'heartbeat.connection-lost', error, status );
+				}
+			}
+		}
+
+		/**
+		 * Clears the error state and fires an event if there is a connection error.
+		 *
+		 * @since 3.8.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function clearErrorState() {
+			// Has connected successfully.
+			settings.hasConnected = true;
+
+			if ( hasConnectionError() ) {
+				settings.errorcount = 0;
+				settings.connectionError = false;
+				$document.trigger( 'heartbeat-connection-restored' );
+				wp.hooks.doAction( 'heartbeat.connection-restored' );
+			}
+		}
+
+		/**
+		 * Gathers the data and connects to the server.
+		 *
+		 * @since 3.6.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function connect() {
+			var ajaxData, heartbeatData;
+
+			// If the connection to the server is slower than the interval,
+			// heartbeat connects as soon as the previous connection's response is received.
+			if ( settings.connecting || settings.suspend ) {
+				return;
+			}
+
+			settings.lastTick = time();
+
+			heartbeatData = $.extend( {}, settings.queue );
+			// Clear the data queue. Anything added after this point will be sent on the next tick.
+			settings.queue = {};
+
+			$document.trigger( 'heartbeat-send', [ heartbeatData ] );
+			wp.hooks.doAction( 'heartbeat.send', heartbeatData );
+
+			ajaxData = {
+				data: heartbeatData,
+				interval: settings.tempInterval ? settings.tempInterval / 1000 : settings.mainInterval / 1000,
+				_nonce: typeof window.heartbeatSettings === 'object' ? window.heartbeatSettings.nonce : '',
+				action: 'heartbeat',
+				screen_id: settings.screenId,
+				has_focus: settings.hasFocus
+			};
+
+			if ( 'customize' === settings.screenId  ) {
+				ajaxData.wp_customize = 'on';
+			}
+
+			settings.connecting = true;
+			settings.xhr = $.ajax({
+				url: settings.url,
+				type: 'post',
+				timeout: 30000, // Throw an error if not completed after 30 seconds.
+				data: ajaxData,
+				dataType: 'json'
+			}).always( function() {
+				settings.connecting = false;
+				scheduleNextTick();
+			}).done( function( response, textStatus, jqXHR ) {
+				var newInterval;
+
+				if ( ! response ) {
+					setErrorState( 'empty' );
+					return;
+				}
+
+				clearErrorState();
+
+				if ( response.nonces_expired ) {
+					$document.trigger( 'heartbeat-nonces-expired' );
+					wp.hooks.doAction( 'heartbeat.nonces-expired' );
+				}
+
+				// Change the interval from PHP.
+				if ( response.heartbeat_interval ) {
+					newInterval = response.heartbeat_interval;
+					delete response.heartbeat_interval;
+				}
+
+				// Update the heartbeat nonce if set.
+				if ( response.heartbeat_nonce && typeof window.heartbeatSettings === 'object' ) {
+					window.heartbeatSettings.nonce = response.heartbeat_nonce;
+					delete response.heartbeat_nonce;
+				}
+
+				// Update the Rest API nonce if set and wp-api loaded.
+				if ( response.rest_nonce && typeof window.wpApiSettings === 'object' ) {
+					window.wpApiSettings.nonce = response.rest_nonce;
+					// This nonce is required for api-fetch through heartbeat.tick.
+					// delete response.rest_nonce;
+				}
+
+				$document.trigger( 'heartbeat-tick', [response, textStatus, jqXHR] );
+				wp.hooks.doAction( 'heartbeat.tick', response, textStatus, jqXHR );
+
+				// Do this last. Can trigger the next XHR if connection time > 5 seconds and newInterval == 'fast'.
+				if ( newInterval ) {
+					interval( newInterval );
+				}
+			}).fail( function( jqXHR, textStatus, error ) {
+				setErrorState( textStatus || 'unknown', jqXHR.status );
+				$document.trigger( 'heartbeat-error', [jqXHR, textStatus, error] );
+				wp.hooks.doAction( 'heartbeat.error', jqXHR, textStatus, error );
+			});
+		}
+
+		/**
+		 * Schedules the next connection.
+		 *
+		 * Fires immediately if the connection time is longer than the interval.
+		 *
+		 * @since 3.8.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function scheduleNextTick() {
+			var delta = time() - settings.lastTick,
+				interval = settings.mainInterval;
+
+			if ( settings.suspend ) {
+				return;
+			}
+
+			if ( ! settings.hasFocus ) {
+				interval = 120000; // 120 seconds. Post locks expire after 150 seconds.
+			} else if ( settings.countdown > 0 && settings.tempInterval ) {
+				interval = settings.tempInterval;
+				settings.countdown--;
+
+				if ( settings.countdown < 1 ) {
+					settings.tempInterval = 0;
+				}
+			}
+
+			if ( settings.minimalInterval && interval < settings.minimalInterval ) {
+				interval = settings.minimalInterval;
+			}
+
+			window.clearTimeout( settings.beatTimer );
+
+			if ( delta < interval ) {
+				settings.beatTimer = window.setTimeout(
+					function() {
+						connect();
+					},
+					interval - delta
+				);
+			} else {
+				connect();
+			}
+		}
+
+		/**
+		 * Sets the internal state when the browser window becomes hidden or loses focus.
+		 *
+		 * @since 3.6.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function blurred() {
+			settings.hasFocus = false;
+		}
+
+		/**
+		 * Sets the internal state when the browser window becomes visible or is in focus.
+		 *
+		 * @since 3.6.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function focused() {
+			settings.userActivity = time();
+
+			// Resume if suspended.
+			resume();
+
+			if ( ! settings.hasFocus ) {
+				settings.hasFocus = true;
+				scheduleNextTick();
+			}
+		}
+
+		/**
+		 * Suspends connecting.
+		 */
+		function suspend() {
+			settings.suspend = true;
+		}
+
+		/**
+		 * Resumes connecting.
+		 */
+		function resume() {
+			settings.suspend = false;
+		}
+
+		/**
+		 * Runs when the user becomes active after a period of inactivity.
+		 *
+		 * @since 3.6.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function userIsActive() {
+			settings.userActivityEvents = false;
+			$document.off( '.wp-heartbeat-active' );
+
+			$('iframe').each( function( i, frame ) {
+				if ( isLocalFrame( frame ) ) {
+					$( frame.contentWindow ).off( '.wp-heartbeat-active' );
+				}
+			});
+
+			focused();
+		}
+
+		/**
+		 * Checks for user activity.
+		 *
+		 * Runs every 30 seconds. Sets 'hasFocus = true' if user is active and the window
+		 * is in the background. Sets 'hasFocus = false' if the user has been inactive
+		 * (no mouse or keyboard activity) for 5 minutes even when the window has focus.
+		 *
+		 * @since 3.8.0
+		 * @access private
+		 *
+		 * @return {void}
+		 */
+		function checkUserActivity() {
+			var lastActive = settings.userActivity ? time() - settings.userActivity : 0;
+
+			// Throttle down when no mouse or keyboard activity for 5 minutes.
+			if ( lastActive > 300000 && settings.hasFocus ) {
+				blurred();
+			}
+
+			// Suspend after 10 minutes of inactivity when suspending is enabled.
+			// Always suspend after 60 minutes of inactivity. This will release the post lock, etc.
+			if ( ( settings.suspendEnabled && lastActive > 600000 ) || lastActive > 3600000 ) {
+				suspend();
+			}
+
+			if ( ! settings.userActivityEvents ) {
+				$document.on( 'mouseover.wp-heartbeat-active keyup.wp-heartbeat-active touchend.wp-heartbeat-active', function() {
+					userIsActive();
+				});
+
+				$('iframe').each( function( i, frame ) {
+					if ( isLocalFrame( frame ) ) {
+						$( frame.contentWindow ).on( 'mouseover.wp-heartbeat-active keyup.wp-heartbeat-active touchend.wp-heartbeat-active', function() {
+							userIsActive();
+						});
+					}
+				});
+
+				settings.userActivityEvents = true;
+			}
+		}
+
+		// Public methods.
+
+		/**
+		 * Checks whether the window (or any local iframe in it) has focus, or the user
+		 * is active.
+		 *
+		 * @since 3.6.0
+		 * @memberOf wp.heartbeat.prototype
+		 *
+		 * @return {boolean} True if the window or the user is active.
+		 */
+		function hasFocus() {
+			return settings.hasFocus;
+		}
+
+		/**
+		 * Checks whether there is a connection error.
+		 *
+		 * @since 3.6.0
+		 *
+		 * @memberOf wp.heartbeat.prototype
+		 *
+		 * @return {boolean} True if a connection error was found.
+		 */
+		function hasConnectionError() {
+			return settings.connectionError;
+		}
+
+		/**
+		 * Connects as soon as possible regardless of 'hasFocus' state.
+		 *
+		 * Will not open two concurrent connections. If a connection is in progress,
+		 * will connect again immediately after the current connection completes.
+		 *
+		 * @since 3.8.0
+		 *
+		 * @memberOf wp.heartbeat.prototype
+		 *
+		 * @return {void}
+		 */
+		function connectNow() {
+			settings.lastTick = 0;
+			scheduleNextTick();
+		}
+
+		/**
+		 * Disables suspending.
+		 *
+		 * Should be used only when Heartbeat is performing critical tasks like
+		 * autosave, post-locking, etc. Using this on many screens may overload
+		 * the user's hosting account if several browser windows/tabs are left open
+		 * for a long time.
+		 *
+		 * @since 3.8.0
+		 *
+		 * @memberOf wp.heartbeat.prototype
+		 *
+		 * @return {void}
+		 */
+		function disableSuspend() {
+			settings.suspendEnabled = false;
+		}
+
+		/**
+		 * Gets/Sets the interval.
+		 *
+		 * When setting to 'fast' or 5, the interval is 5 seconds for the next 30 ticks
+		 * (for 2 minutes and 30 seconds) by default. In this case the number of 'ticks'
+		 * can be passed as second argument. If the window doesn't have focus,
+		 * the interval slows down to 2 minutes.
+		 *
+		 * @since 3.6.0
+		 *
+		 * @memberOf wp.heartbeat.prototype
+		 *
+		 * @param {string|number} speed Interval: 'fast' or 5, 15, 30, 60, 120.
+		 *                              Fast equals 5.
+		 * @param {string}        ticks Tells how many ticks before the interval reverts
+		 *                              back. Used with speed = 'fast' or 5.
+		 *
+		 * @return {number} Current interval in seconds.
+		 */
+		function interval( speed, ticks ) {
+			var newInterval,
+				oldInterval = settings.tempInterval ? settings.tempInterval : settings.mainInterval;
+
+			if ( speed ) {
+				switch ( speed ) {
+					case 'fast':
+					case 5:
+						newInterval = 5000;
+						break;
+					case 15:
+						newInterval = 15000;
+						break;
+					case 30:
+						newInterval = 30000;
+						break;
+					case 60:
+						newInterval = 60000;
+						break;
+					case 120:
+						newInterval = 120000;
+						break;
+					case 'long-polling':
+						// Allow long polling (experimental).
+						settings.mainInterval = 0;
+						return 0;
+					default:
+						newInterval = settings.originalInterval;
+				}
+
+				if ( settings.minimalInterval && newInterval < settings.minimalInterval ) {
+					newInterval = settings.minimalInterval;
+				}
+
+				if ( 5000 === newInterval ) {
+					ticks = parseInt( ticks, 10 ) || 30;
+					ticks = ticks < 1 || ticks > 30 ? 30 : ticks;
+
+					settings.countdown = ticks;
+					settings.tempInterval = newInterval;
+				} else {
+					settings.countdown = 0;
+					settings.tempInterval = 0;
+					settings.mainInterval = newInterval;
+				}
+
+				/*
+				 * Change the next connection time if new interval has been set.
+				 * Will connect immediately if the time since the last connection
+				 * is greater than the new interval.
+				 */
+				if ( newInterval !== oldInterval ) {
+					scheduleNextTick();
+				}
+			}
+
+			return settings.tempInterval ? settings.tempInterval / 1000 : settings.mainInterval / 1000;
+		}
+
+		/**
+		 * Enqueues data to send with the next XHR.
+		 *
+		 * As the data is send asynchronously, this function doesn't return the XHR
+		 * response. To see the response, use the custom jQuery event 'heartbeat-tick'
+		 * on the document, example:
+		 *		$(document).on( 'heartbeat-tick.myname', function( event, data, textStatus, jqXHR ) {
+		 *			// code
+		 *		});
+		 * If the same 'handle' is used more than once, the data is not overwritten when
+		 * the third argument is 'true'. Use `wp.heartbeat.isQueued('handle')` to see if
+		 * any data is already queued for that handle.
+		 *
+		 * @since 3.6.0
+		 *
+		 * @memberOf wp.heartbeat.prototype
+		 *
+		 * @param {string}  handle      Unique handle for the data, used in PHP to
+		 *                              receive the data.
+		 * @param {*}       data        The data to send.
+		 * @param {boolean} noOverwrite Whether to overwrite existing data in the queue.
+		 *
+		 * @return {boolean} True if the data was queued.
+		 */
+		function enqueue( handle, data, noOverwrite ) {
+			if ( handle ) {
+				if ( noOverwrite && this.isQueued( handle ) ) {
+					return false;
+				}
+
+				settings.queue[handle] = data;
+				return true;
+			}
+			return false;
+		}
+
+		/**
+		 * Checks if data with a particular handle is queued.
+		 *
+		 * @since 3.6.0
+		 *
+		 * @param {string} handle The handle for the data.
+		 *
+		 * @return {boolean} True if the data is queued with this handle.
+		 */
+		function isQueued( handle ) {
+			if ( handle ) {
+				return settings.queue.hasOwnProperty( handle );
+			}
+		}
+
+		/**
+		 * Removes data with a particular handle from the queue.
+		 *
+		 * @since 3.7.0
+		 *
+		 * @memberOf wp.heartbeat.prototype
+		 *
+		 * @param {string} handle The handle for the data.
+		 *
+		 * @return {void}
+		 */
+		function dequeue( handle ) {
+			if ( handle ) {
+				delete settings.queue[handle];
+			}
+		}
+
+		/**
+		 * Gets data that was enqueued with a particular handle.
+		 *
+		 * @since 3.7.0
+		 *
+		 * @memberOf wp.heartbeat.prototype
+		 *
+		 * @param {string} handle The handle for the data.
+		 *
+		 * @return {*} The data or undefined.
+		 */
+		function getQueuedItem( handle ) {
+			if ( handle ) {
+				return this.isQueued( handle ) ? settings.queue[handle] : undefined;
+			}
+		}
+
+		initialize();
+
+		// Expose public methods.
+		return {
+			hasFocus: hasFocus,
+			connectNow: connectNow,
+			disableSuspend: disableSuspend,
+			interval: interval,
+			hasConnectionError: hasConnectionError,
+			enqueue: enqueue,
+			dequeue: dequeue,
+			isQueued: isQueued,
+			getQueuedItem: getQueuedItem
+		};
+	};
+
+	/**
+	 * Ensure the global `wp` object exists.
+	 *
+	 * @namespace wp
+	 */
+	window.wp = window.wp || {};
+
+	/**
+	 * Contains the Heartbeat API.
+	 *
+	 * @namespace wp.heartbeat
+	 * @type {Heartbeat}
+	 */
+	window.wp.heartbeat = new Heartbeat();
+
+}( jQuery, window ));