]> scripts.mit.edu Git - autoinstalls/wordpress.git/blobdiff - wp-includes/js/customize-preview.js
WordPress 4.7-scripts
[autoinstalls/wordpress.git] / wp-includes / js / customize-preview.js
index f5569ed13d05a3a827f03ee673de3a23cd43e526..a4cb196dc10fbd287a7f8db1c3bcc5f448674ed4 100644 (file)
@@ -3,7 +3,68 @@
  */
 (function( exports, $ ){
        var api = wp.customize,
-               debounce;
+               debounce,
+               currentHistoryState = {};
+
+       /*
+        * Capture the state that is passed into history.replaceState() and history.pushState()
+        * and also which is returned in the popstate event so that when the changeset_uuid
+        * gets updated when transitioning to a new changeset there the current state will
+        * be supplied in the call to history.replaceState().
+        */
+       ( function( history ) {
+               var injectUrlWithState;
+
+               if ( ! history.replaceState ) {
+                       return;
+               }
+
+               /**
+                * Amend the supplied URL with the customized state.
+                *
+                * @since 4.7.0
+                * @access private
+                *
+                * @param {string} url URL.
+                * @returns {string} URL with customized state.
+                */
+               injectUrlWithState = function( url ) {
+                       var urlParser, oldQueryParams, newQueryParams;
+                       urlParser = document.createElement( 'a' );
+                       urlParser.href = url;
+                       oldQueryParams = api.utils.parseQueryString( location.search.substr( 1 ) );
+                       newQueryParams = api.utils.parseQueryString( urlParser.search.substr( 1 ) );
+
+                       newQueryParams.customize_changeset_uuid = oldQueryParams.customize_changeset_uuid;
+                       if ( oldQueryParams.customize_theme ) {
+                               newQueryParams.customize_theme = oldQueryParams.customize_theme;
+                       }
+                       if ( oldQueryParams.customize_messenger_channel ) {
+                               newQueryParams.customize_messenger_channel = oldQueryParams.customize_messenger_channel;
+                       }
+                       urlParser.search = $.param( newQueryParams );
+                       return urlParser.href;
+               };
+
+               history.replaceState = ( function( nativeReplaceState ) {
+                       return function historyReplaceState( data, title, url ) {
+                               currentHistoryState = data;
+                               return nativeReplaceState.call( history, data, title, injectUrlWithState( url ) );
+                       };
+               } )( history.replaceState );
+
+               history.pushState = ( function( nativePushState ) {
+                       return function historyPushState( data, title, url ) {
+                               currentHistoryState = data;
+                               return nativePushState.call( history, data, title, injectUrlWithState( url ) );
+                       };
+               } )( history.pushState );
+
+               window.addEventListener( 'popstate', function( event ) {
+                       currentHistoryState = event.state;
+               } );
+
+       }( history ) );
 
        /**
         * Returns a debounced version of the function.
                 * @param {object} options - Extend any instance parameter or method with this object.
                 */
                initialize: function( params, options ) {
-                       var self = this;
+                       var preview = this, urlParser = document.createElement( 'a' );
+
+                       api.Messenger.prototype.initialize.call( preview, params, options );
+
+                       urlParser.href = preview.origin();
+                       preview.add( 'scheme', urlParser.protocol.replace( /:$/, '' ) );
+
+                       preview.body = $( document.body );
+                       preview.window = $( window );
+
+                       if ( api.settings.channel ) {
+
+                               // If in an iframe, then intercept the link clicks and form submissions.
+                               preview.body.on( 'click.preview', 'a', function( event ) {
+                                       preview.handleLinkClick( event );
+                               } );
+                               preview.body.on( 'submit.preview', 'form', function( event ) {
+                                       preview.handleFormSubmit( event );
+                               } );
+
+                               preview.window.on( 'scroll.preview', debounce( function() {
+                                       preview.send( 'scroll', preview.window.scrollTop() );
+                               }, 200 ) );
+
+                               preview.bind( 'scroll', function( distance ) {
+                                       preview.window.scrollTop( distance );
+                               });
+                       }
+               },
+
+               /**
+                * Handle link clicks in preview.
+                *
+                * @since 4.7.0
+                * @access public
+                *
+                * @param {jQuery.Event} event Event.
+                */
+               handleLinkClick: function( event ) {
+                       var preview = this, link, isInternalJumpLink;
+                       link = $( event.target );
+
+                       // No-op if the anchor is not a link.
+                       if ( _.isUndefined( link.attr( 'href' ) ) ) {
+                               return;
+                       }
+
+                       isInternalJumpLink = ( '#' === link.attr( 'href' ).substr( 0, 1 ) );
 
-                       api.Messenger.prototype.initialize.call( this, params, options );
+                       // Allow internal jump links to behave normally without preventing default.
+                       if ( isInternalJumpLink ) {
+                               return;
+                       }
 
-                       this.body = $( document.body );
-                       this.body.on( 'click.preview', 'a', function( event ) {
-                               var link, isInternalJumpLink;
-                               link = $( this );
-                               isInternalJumpLink = ( '#' === link.attr( 'href' ).substr( 0, 1 ) );
+                       // If the link is not previewable, prevent the browser from navigating to it.
+                       if ( ! api.isLinkPreviewable( link[0] ) ) {
+                               wp.a11y.speak( api.settings.l10n.linkUnpreviewable );
                                event.preventDefault();
+                               return;
+                       }
+
+                       // Prevent initiating navigating from click and instead rely on sending url message to pane.
+                       event.preventDefault();
+
+                       /*
+                        * Note the shift key is checked so shift+click on widgets or
+                        * nav menu items can just result on focusing on the corresponding
+                        * control instead of also navigating to the URL linked to.
+                        */
+                       if ( event.shiftKey ) {
+                               return;
+                       }
+
+                       // Note: It's not relevant to send scroll because sending url message will have the same effect.
+                       preview.send( 'url', link.prop( 'href' ) );
+               },
+
+               /**
+                * Handle form submit.
+                *
+                * @since 4.7.0
+                * @access public
+                *
+                * @param {jQuery.Event} event Event.
+                */
+               handleFormSubmit: function( event ) {
+                       var preview = this, urlParser, form;
+                       urlParser = document.createElement( 'a' );
+                       form = $( event.target );
+                       urlParser.href = form.prop( 'action' );
+
+                       // If the link is not previewable, prevent the browser from navigating to it.
+                       if ( 'GET' !== form.prop( 'method' ).toUpperCase() || ! api.isLinkPreviewable( urlParser ) ) {
+                               wp.a11y.speak( api.settings.l10n.formUnpreviewable );
+                               event.preventDefault();
+                               return;
+                       }
+
+                       /*
+                        * If the default wasn't prevented already (in which case the form
+                        * submission is already being handled by JS), and if it has a GET
+                        * request method, then take the serialized form data and add it as
+                        * a query string to the action URL and send this in a url message
+                        * to the customizer pane so that it will be loaded. If the form's
+                        * action points to a non-previewable URL, the customizer pane's
+                        * previewUrl setter will reject it so that the form submission is
+                        * a no-op, which is the same behavior as when clicking a link to an
+                        * external site in the preview.
+                        */
+                       if ( ! event.isDefaultPrevented() ) {
+                               if ( urlParser.search.length > 1 ) {
+                                       urlParser.search += '&';
+                               }
+                               urlParser.search += form.serialize();
+                               preview.send( 'url', urlParser.href );
+                       }
+
+                       // Prevent default since navigation should be done via sending url message or via JS submit handler.
+                       event.preventDefault();
+               }
+       });
+
+       /**
+        * Inject the changeset UUID into links in the document.
+        *
+        * @since 4.7.0
+        * @access protected
+        *
+        * @access private
+        * @returns {void}
+        */
+       api.addLinkPreviewing = function addLinkPreviewing() {
+               var linkSelectors = 'a[href], area';
+
+               // Inject links into initial document.
+               $( document.body ).find( linkSelectors ).each( function() {
+                       api.prepareLinkPreview( this );
+               } );
 
-                               if ( isInternalJumpLink && '#' !== link.attr( 'href' ) ) {
-                                       $( link.attr( 'href' ) ).each( function() {
-                                               this.scrollIntoView();
+               // Inject links for new elements added to the page.
+               if ( 'undefined' !== typeof MutationObserver ) {
+                       api.mutationObserver = new MutationObserver( function( mutations ) {
+                               _.each( mutations, function( mutation ) {
+                                       $( mutation.target ).find( linkSelectors ).each( function() {
+                                               api.prepareLinkPreview( this );
                                        } );
+                               } );
+                       } );
+                       api.mutationObserver.observe( document.documentElement, {
+                               childList: true,
+                               subtree: true
+                       } );
+               } else {
+
+                       // If mutation observers aren't available, fallback to just-in-time injection.
+                       $( document.documentElement ).on( 'click focus mouseover', linkSelectors, function() {
+                               api.prepareLinkPreview( this );
+                       } );
+               }
+       };
+
+       /**
+        * Should the supplied link is previewable.
+        *
+        * @since 4.7.0
+        * @access public
+        *
+        * @param {HTMLAnchorElement|HTMLAreaElement} element Link element.
+        * @param {string} element.search Query string.
+        * @param {string} element.pathname Path.
+        * @param {string} element.host Host.
+        * @param {object} [options]
+        * @param {object} [options.allowAdminAjax=false] Allow admin-ajax.php requests.
+        * @returns {boolean} Is appropriate for changeset link.
+        */
+       api.isLinkPreviewable = function isLinkPreviewable( element, options ) {
+               var matchesAllowedUrl, parsedAllowedUrl, args;
+
+               args = _.extend( {}, { allowAdminAjax: false }, options || {} );
+
+               if ( 'javascript:' === element.protocol ) { // jshint ignore:line
+                       return true;
+               }
+
+               // Only web URLs can be previewed.
+               if ( 'https:' !== element.protocol && 'http:' !== element.protocol ) {
+                       return false;
+               }
+
+               parsedAllowedUrl = document.createElement( 'a' );
+               matchesAllowedUrl = ! _.isUndefined( _.find( api.settings.url.allowed, function( allowedUrl ) {
+                       parsedAllowedUrl.href = allowedUrl;
+                       return parsedAllowedUrl.protocol === element.protocol && parsedAllowedUrl.host === element.host && 0 === element.pathname.indexOf( parsedAllowedUrl.pathname.replace( /\/$/, '' ) );
+               } ) );
+               if ( ! matchesAllowedUrl ) {
+                       return false;
+               }
+
+               // Skip wp login and signup pages.
+               if ( /\/wp-(login|signup)\.php$/.test( element.pathname ) ) {
+                       return false;
+               }
+
+               // Allow links to admin ajax as faux frontend URLs.
+               if ( /\/wp-admin\/admin-ajax\.php$/.test( element.pathname ) ) {
+                       return args.allowAdminAjax;
+               }
+
+               // Disallow links to admin, includes, and content.
+               if ( /\/wp-(admin|includes|content)(\/|$)/.test( element.pathname ) ) {
+                       return false;
+               }
+
+               return true;
+       };
+
+       /**
+        * Inject the customize_changeset_uuid query param into links on the frontend.
+        *
+        * @since 4.7.0
+        * @access protected
+        *
+        * @param {HTMLAnchorElement|HTMLAreaElement} element Link element.
+        * @param {string} element.search Query string.
+        * @param {string} element.host Host.
+        * @param {string} element.protocol Protocol.
+        * @returns {void}
+        */
+       api.prepareLinkPreview = function prepareLinkPreview( element ) {
+               var queryParams;
+
+               // Skip links in admin bar.
+               if ( $( element ).closest( '#wpadminbar' ).length ) {
+                       return;
+               }
+
+               // Ignore links with href="#" or href="#id".
+               if ( '#' === $( element ).attr( 'href' ).substr( 0, 1 ) ) {
+                       return;
+               }
+
+               // Make sure links in preview use HTTPS if parent frame uses HTTPS.
+               if ( api.settings.channel && 'https' === api.preview.scheme.get() && 'http:' === element.protocol && -1 !== api.settings.url.allowedHosts.indexOf( element.host ) ) {
+                       element.protocol = 'https:';
+               }
+
+               if ( ! api.isLinkPreviewable( element ) ) {
+
+                       // Style link as unpreviewable only if previewing in iframe; if previewing on frontend, links will be allowed to work normally.
+                       if ( api.settings.channel ) {
+                               $( element ).addClass( 'customize-unpreviewable' );
+                       }
+                       return;
+               }
+               $( element ).removeClass( 'customize-unpreviewable' );
+
+               queryParams = api.utils.parseQueryString( element.search.substring( 1 ) );
+               queryParams.customize_changeset_uuid = api.settings.changeset.uuid;
+               if ( ! api.settings.theme.active ) {
+                       queryParams.customize_theme = api.settings.theme.stylesheet;
+               }
+               if ( api.settings.channel ) {
+                       queryParams.customize_messenger_channel = api.settings.channel;
+               }
+               element.search = $.param( queryParams );
+
+               // Prevent links from breaking out of preview iframe.
+               if ( api.settings.channel ) {
+                       element.target = '_self';
+               }
+       };
+
+       /**
+        * Inject the changeset UUID into Ajax requests.
+        *
+        * @since 4.7.0
+        * @access protected
+        *
+        * @return {void}
+        */
+       api.addRequestPreviewing = function addRequestPreviewing() {
+
+               /**
+                * Rewrite Ajax requests to inject customizer state.
+                *
+                * @param {object} options Options.
+                * @param {string} options.type Type.
+                * @param {string} options.url URL.
+                * @param {object} originalOptions Original options.
+                * @param {XMLHttpRequest} xhr XHR.
+                * @returns {void}
+                */
+               var prefilterAjax = function( options, originalOptions, xhr ) {
+                       var urlParser, queryParams, requestMethod, dirtyValues = {};
+                       urlParser = document.createElement( 'a' );
+                       urlParser.href = options.url;
+
+                       // Abort if the request is not for this site.
+                       if ( ! api.isLinkPreviewable( urlParser, { allowAdminAjax: true } ) ) {
+                               return;
+                       }
+                       queryParams = api.utils.parseQueryString( urlParser.search.substring( 1 ) );
+
+                       // Note that _dirty flag will be cleared with changeset updates.
+                       api.each( function( setting ) {
+                               if ( setting._dirty ) {
+                                       dirtyValues[ setting.id ] = setting.get();
                                }
+                       } );
 
-                               /*
-                                * Note the shift key is checked so shift+click on widgets or
-                                * nav menu items can just result on focusing on the corresponding
-                                * control instead of also navigating to the URL linked to.
-                                */
-                               if ( event.shiftKey || isInternalJumpLink ) {
-                                       return;
+                       if ( ! _.isEmpty( dirtyValues ) ) {
+                               requestMethod = options.type.toUpperCase();
+
+                               // Override underlying request method to ensure unsaved changes to changeset can be included (force Backbone.emulateHTTP).
+                               if ( 'POST' !== requestMethod ) {
+                                       xhr.setRequestHeader( 'X-HTTP-Method-Override', requestMethod );
+                                       queryParams._method = requestMethod;
+                                       options.type = 'POST';
                                }
-                               self.send( 'scroll', 0 );
-                               self.send( 'url', link.prop( 'href' ) );
-                       });
 
-                       // You cannot submit forms.
-                       // @todo: Allow form submissions by mixing $_POST data with the customize setting $_POST data.
-                       this.body.on( 'submit.preview', 'form', function( event ) {
-                               event.preventDefault();
-                       });
+                               // Amend the post data with the customized values.
+                               if ( options.data ) {
+                                       options.data += '&';
+                               } else {
+                                       options.data = '';
+                               }
+                               options.data += $.param( {
+                                       customized: JSON.stringify( dirtyValues )
+                               } );
+                       }
 
-                       this.window = $( window );
-                       this.window.on( 'scroll.preview', debounce( function() {
-                               self.send( 'scroll', self.window.scrollTop() );
-                       }, 200 ));
+                       // Include customized state query params in URL.
+                       queryParams.customize_changeset_uuid = api.settings.changeset.uuid;
+                       if ( ! api.settings.theme.active ) {
+                               queryParams.customize_theme = api.settings.theme.stylesheet;
+                       }
+                       urlParser.search = $.param( queryParams );
+                       options.url = urlParser.href;
+               };
 
-                       this.bind( 'scroll', function( distance ) {
-                               self.window.scrollTop( distance );
-                       });
+               $.ajaxPrefilter( prefilterAjax );
+       };
+
+       /**
+        * Inject changeset UUID into forms, allowing preview to persist through submissions.
+        *
+        * @since 4.7.0
+        * @access protected
+        *
+        * @returns {void}
+        */
+       api.addFormPreviewing = function addFormPreviewing() {
+
+               // Inject inputs for forms in initial document.
+               $( document.body ).find( 'form' ).each( function() {
+                       api.prepareFormPreview( this );
+               } );
+
+               // Inject inputs for new forms added to the page.
+               if ( 'undefined' !== typeof MutationObserver ) {
+                       api.mutationObserver = new MutationObserver( function( mutations ) {
+                               _.each( mutations, function( mutation ) {
+                                       $( mutation.target ).find( 'form' ).each( function() {
+                                               api.prepareFormPreview( this );
+                                       } );
+                               } );
+                       } );
+                       api.mutationObserver.observe( document.documentElement, {
+                               childList: true,
+                               subtree: true
+                       } );
                }
-       });
+       };
+
+       /**
+        * Inject changeset into form inputs.
+        *
+        * @since 4.7.0
+        * @access protected
+        *
+        * @param {HTMLFormElement} form Form.
+        * @returns {void}
+        */
+       api.prepareFormPreview = function prepareFormPreview( form ) {
+               var urlParser, stateParams = {};
+
+               if ( ! form.action ) {
+                       form.action = location.href;
+               }
+
+               urlParser = document.createElement( 'a' );
+               urlParser.href = form.action;
+
+               // Make sure forms in preview use HTTPS if parent frame uses HTTPS.
+               if ( api.settings.channel && 'https' === api.preview.scheme.get() && 'http:' === urlParser.protocol && -1 !== api.settings.url.allowedHosts.indexOf( urlParser.host ) ) {
+                       urlParser.protocol = 'https:';
+                       form.action = urlParser.href;
+               }
+
+               if ( 'GET' !== form.method.toUpperCase() || ! api.isLinkPreviewable( urlParser ) ) {
+
+                       // Style form as unpreviewable only if previewing in iframe; if previewing on frontend, all forms will be allowed to work normally.
+                       if ( api.settings.channel ) {
+                               $( form ).addClass( 'customize-unpreviewable' );
+                       }
+                       return;
+               }
+               $( form ).removeClass( 'customize-unpreviewable' );
+
+               stateParams.customize_changeset_uuid = api.settings.changeset.uuid;
+               if ( ! api.settings.theme.active ) {
+                       stateParams.customize_theme = api.settings.theme.stylesheet;
+               }
+               if ( api.settings.channel ) {
+                       stateParams.customize_messenger_channel = api.settings.channel;
+               }
+
+               _.each( stateParams, function( value, name ) {
+                       var input = $( form ).find( 'input[name="' + name + '"]' );
+                       if ( input.length ) {
+                               input.val( value );
+                       } else {
+                               $( form ).prepend( $( '<input>', {
+                                       type: 'hidden',
+                                       name: name,
+                                       value: value
+                               } ) );
+                       }
+               } );
+
+               // Prevent links from breaking out of preview iframe.
+               if ( api.settings.channel ) {
+                       form.target = '_self';
+               }
+       };
+
+       /**
+        * Watch current URL and send keep-alive (heartbeat) messages to the parent.
+        *
+        * Keep the customizer pane notified that the preview is still alive
+        * and that the user hasn't navigated to a non-customized URL.
+        *
+        * @since 4.7.0
+        * @access protected
+        */
+       api.keepAliveCurrentUrl = ( function() {
+               var previousPathName = location.pathname,
+                       previousQueryString = location.search.substr( 1 ),
+                       previousQueryParams = null,
+                       stateQueryParams = [ 'customize_theme', 'customize_changeset_uuid', 'customize_messenger_channel' ];
+
+               return function keepAliveCurrentUrl() {
+                       var urlParser, currentQueryParams;
+
+                       // Short-circuit with keep-alive if previous URL is identical (as is normal case).
+                       if ( previousQueryString === location.search.substr( 1 ) && previousPathName === location.pathname ) {
+                               api.preview.send( 'keep-alive' );
+                               return;
+                       }
+
+                       urlParser = document.createElement( 'a' );
+                       if ( null === previousQueryParams ) {
+                               urlParser.search = previousQueryString;
+                               previousQueryParams = api.utils.parseQueryString( previousQueryString );
+                               _.each( stateQueryParams, function( name ) {
+                                       delete previousQueryParams[ name ];
+                               } );
+                       }
+
+                       // Determine if current URL minus customized state params and URL hash.
+                       urlParser.href = location.href;
+                       currentQueryParams = api.utils.parseQueryString( urlParser.search.substr( 1 ) );
+                       _.each( stateQueryParams, function( name ) {
+                               delete currentQueryParams[ name ];
+                       } );
+
+                       if ( previousPathName !== location.pathname || ! _.isEqual( previousQueryParams, currentQueryParams ) ) {
+                               urlParser.search = $.param( currentQueryParams );
+                               urlParser.hash = '';
+                               api.settings.url.self = urlParser.href;
+                               api.preview.send( 'ready', {
+                                       currentUrl: api.settings.url.self,
+                                       activePanels: api.settings.activePanels,
+                                       activeSections: api.settings.activeSections,
+                                       activeControls: api.settings.activeControls,
+                                       settingValidities: api.settings.settingValidities
+                               } );
+                       } else {
+                               api.preview.send( 'keep-alive' );
+                       }
+                       previousQueryParams = currentQueryParams;
+                       previousQueryString = location.search.substr( 1 );
+                       previousPathName = location.pathname;
+               };
+       } )();
+
+       api.settingPreviewHandlers = {
+
+               /**
+                * Preview changes to custom logo.
+                *
+                * @param {number} attachmentId Attachment ID for custom logo.
+                * @returns {void}
+                */
+               custom_logo: function( attachmentId ) {
+                       $( 'body' ).toggleClass( 'wp-custom-logo', !! attachmentId );
+               },
+
+               /**
+                * Preview changes to custom css.
+                *
+                * @param {string} value Custom CSS..
+                * @returns {void}
+                */
+               custom_css: function( value ) {
+                       $( '#wp-custom-css' ).text( value );
+               },
+
+               /**
+                * Preview changes to any of the background settings.
+                *
+                * @returns {void}
+                */
+               background: function() {
+                       var css = '', settings = {};
+
+                       _.each( ['color', 'image', 'preset', 'position_x', 'position_y', 'size', 'repeat', 'attachment'], function( prop ) {
+                               settings[ prop ] = api( 'background_' + prop );
+                       } );
+
+                       /*
+                        * The body will support custom backgrounds if either the color or image are set.
+                        *
+                        * See get_body_class() in /wp-includes/post-template.php
+                        */
+                       $( document.body ).toggleClass( 'custom-background', !! ( settings.color() || settings.image() ) );
+
+                       if ( settings.color() ) {
+                               css += 'background-color: ' + settings.color() + ';';
+                       }
+
+                       if ( settings.image() ) {
+                               css += 'background-image: url("' + settings.image() + '");';
+                               css += 'background-size: ' + settings.size() + ';';
+                               css += 'background-position: ' + settings.position_x() + ' ' + settings.position_y() + ';';
+                               css += 'background-repeat: ' + settings.repeat() + ';';
+                               css += 'background-attachment: ' + settings.attachment() + ';';
+                       }
+
+                       $( '#custom-background-css' ).text( 'body.custom-background { ' + css + ' }' );
+               }
+       };
 
        $( function() {
                var bg, setValue;
                        channel: api.settings.channel
                });
 
+               api.addLinkPreviewing();
+               api.addRequestPreviewing();
+               api.addFormPreviewing();
+
                /**
                 * Create/update a setting value.
                 *
                });
 
                api.preview.bind( 'sync', function( events ) {
+
+                       /*
+                        * Delete any settings that already exist locally which haven't been
+                        * modified in the controls while the preview was loading. This prevents
+                        * situations where the JS value being synced from the pane may differ
+                        * from the PHP-sanitized JS value in the preview which causes the
+                        * non-sanitized JS value to clobber the PHP-sanitized value. This
+                        * is particularly important for selective refresh partials that
+                        * have a fallback refresh behavior since infinite refreshing would
+                        * result.
+                        */
+                       if ( events.settings && events['settings-modified-while-loading'] ) {
+                               _.each( _.keys( events.settings ), function( syncedSettingId ) {
+                                       if ( api.has( syncedSettingId ) && ! events['settings-modified-while-loading'][ syncedSettingId ] ) {
+                                               delete events.settings[ syncedSettingId ];
+                                       }
+                               } );
+                       }
+
                        $.each( events, function( event, args ) {
                                api.preview.trigger( event, args );
                        });
                        api.preview.send( 'nonce', api.settings.nonce );
 
                        api.preview.send( 'documentTitle', document.title );
+
+                       // Send scroll in case of loading via non-refresh.
+                       api.preview.send( 'scroll', $( window ).scrollTop() );
                });
 
                api.preview.bind( 'saved', function( response ) {
+
+                       if ( response.next_changeset_uuid ) {
+                               api.settings.changeset.uuid = response.next_changeset_uuid;
+
+                               // Update UUIDs in links and forms.
+                               $( document.body ).find( 'a[href], area' ).each( function() {
+                                       api.prepareLinkPreview( this );
+                               } );
+                               $( document.body ).find( 'form' ).each( function() {
+                                       api.prepareFormPreview( this );
+                               } );
+
+                               /*
+                                * Replace the UUID in the URL. Note that the wrapped history.replaceState()
+                                * will handle injecting the current api.settings.changeset.uuid into the URL,
+                                * so this is merely to trigger that logic.
+                                */
+                               if ( history.replaceState ) {
+                                       history.replaceState( currentHistoryState, '', location.href );
+                               }
+                       }
+
                        api.trigger( 'saved', response );
                } );
 
-               api.bind( 'saved', function() {
-                       api.each( function( setting ) {
-                               setting._dirty = false;
+               /*
+                * Clear dirty flag for settings when saved to changeset so that they
+                * won't be needlessly included in selective refresh or ajax requests.
+                */
+               api.preview.bind( 'changeset-saved', function( data ) {
+                       _.each( data.saved_changeset_values, function( value, settingId ) {
+                               var setting = api( settingId );
+                               if ( setting && _.isEqual( setting.get(), value ) ) {
+                                       setting._dirty = false;
+                               }
                        } );
                } );
 
                 * containers and controls are active.
                 */
                api.preview.send( 'ready', {
+                       currentUrl: api.settings.url.self,
                        activePanels: api.settings.activePanels,
                        activeSections: api.settings.activeSections,
                        activeControls: api.settings.activeControls,
                        settingValidities: api.settings.settingValidities
                } );
 
+               // Send ready when URL changes via JS.
+               setInterval( api.keepAliveCurrentUrl, api.settings.timeouts.keepAliveSend );
+
                // Display a loading indicator when preview is reloading, and remove on failure.
                api.preview.bind( 'loading-initiated', function () {
                        $( 'body' ).addClass( 'wp-customizer-unloading' );
                });
 
                /* Custom Backgrounds */
-               bg = $.map(['color', 'image', 'position_x', 'repeat', 'attachment'], function( prop ) {
+               bg = $.map( ['color', 'image', 'preset', 'position_x', 'position_y', 'size', 'repeat', 'attachment'], function( prop ) {
                        return 'background_' + prop;
-               });
-
-               api.when.apply( api, bg ).done( function( color, image, position_x, repeat, attachment ) {
-                       var body = $(document.body),
-                               head = $('head'),
-                               style = $('#custom-background-css'),
-                               update;
-
-                       update = function() {
-                               var css = '';
-
-                               // The body will support custom backgrounds if either
-                               // the color or image are set.
-                               //
-                               // See get_body_class() in /wp-includes/post-template.php
-                               body.toggleClass( 'custom-background', !! ( color() || image() ) );
-
-                               if ( color() )
-                                       css += 'background-color: ' + color() + ';';
-
-                               if ( image() ) {
-                                       css += 'background-image: url("' + image() + '");';
-                                       css += 'background-position: top ' + position_x() + ';';
-                                       css += 'background-repeat: ' + repeat() + ';';
-                                       css += 'background-attachment: ' + attachment() + ';';
-                               }
-
-                               // Refresh the stylesheet by removing and recreating it.
-                               style.remove();
-                               style = $('<style type="text/css" id="custom-background-css">body.custom-background { ' + css + ' }</style>').appendTo( head );
-                       };
+               } );
 
+               api.when.apply( api, bg ).done( function() {
                        $.each( arguments, function() {
-                               this.bind( update );
+                               this.bind( api.settingPreviewHandlers.background );
                        });
                });
 
                 *
                 * @since 4.5.0
                 */
-               api( 'custom_logo', function( setting ) {
-                       $( 'body' ).toggleClass( 'wp-custom-logo', !! setting.get() );
-                       setting.bind( function( attachmentId ) {
-                               $( 'body' ).toggleClass( 'wp-custom-logo', !! attachmentId );
-                       } );
+               api( 'custom_logo', function ( setting ) {
+                       api.settingPreviewHandlers.custom_logo.call( setting, setting.get() );
+                       setting.bind( api.settingPreviewHandlers.custom_logo );
+               } );
+
+               api( 'custom_css[' + api.settings.theme.stylesheet + ']', function( setting ) {
+                       setting.bind( api.settingPreviewHandlers.custom_css );
                } );
 
                api.trigger( 'preview-ready' );