/*
* Script run inside a Customizer preview frame.
*
* @output wp-includes/js/customize-preview.js
*/
(function( exports, $ ){
var api = wp.customize,
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.
* @return {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_autosaved ) {
newQueryParams.customize_autosaved = 'on';
}
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, 'string' === typeof url && url.length > 0 ? injectUrlWithState( url ) : url );
};
} )( history.replaceState );

history.pushState = ( function( nativePushState ) {
return function historyPushState( data, title, url ) {
currentHistoryState = data;
return nativePushState.call( history, data, title, 'string' === typeof url && url.length > 0 ? injectUrlWithState( url ) : url );
};
} )( history.pushState );

window.addEventListener( 'popstate', function( event ) {
currentHistoryState = event.state;
} );

}( history ) );

/**
* Returns a debounced version of the function.
*
* @todo Require Underscore.js for this file and retire this.
*/
debounce = function( fn, delay, context ) {
var timeout;
return function() {
var args = arguments;

context = context || this;

clearTimeout( timeout );
timeout = setTimeout( function() {
timeout = null;
fn.apply( context, args );
}, delay );
};
};

/**
* @memberOf wp.customize
* @alias wp.customize.Preview
*
* @constructor
* @augments wp.customize.Messenger
* @augments wp.customize.Class
* @mixes wp.customize.Events
*/
api.Preview = api.Messenger.extend(/** @lends wp.customize.Preview.prototype */{
/**
* @param {Object} params - Parameters to configure the messenger.
* @param {Object} options - Extend any instance parameter or method with this object.
*/
initialize: function( params, options ) {
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 ).closest( 'a' );

// No-op if the anchor is not a link.
if ( _.isUndefined( link.attr( 'href' ) ) ) {
return;
}

// Allow internal jump links and JS links to behave normally without preventing default.
isInternalJumpLink = ( '#' === link.attr( 'href' ).substr( 0, 1 ) );
if ( isInternalJumpLink || ! /^https?:$/.test( link.prop( 'protocol' ) ) ) {
return;
}

// 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
*
* @return {void}
*/
api.addLinkPreviewing = function addLinkPreviewing() {
var linkSelectors = 'a[href], area[href]';

// Inject links into initial document.
$( document.body ).find( linkSelectors ).each( function() {
api.prepareLinkPreview( this );
} );

// 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.
* @return {boolean} Is appropriate for changeset link.
*/
api.isLinkPreviewable = function isLinkPreviewable( element, options ) {
var matchesAllowedUrl, parsedAllowedUrl, args, elementHost;

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;
}

elementHost = element.host.replace( /:(80|443)$/, '' );
parsedAllowedUrl = document.createElement( 'a' );
matchesAllowedUrl = ! _.isUndefined( _.find( api.settings.url.allowed, function( allowedUrl ) {
parsedAllowedUrl.href = allowedUrl;
return parsedAllowedUrl.protocol === element.protocol && parsedAllowedUrl.host.replace( /:(80|443)$/, '' ) === elementHost && 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.
* @return {void}
*/
api.prepareLinkPreview = function prepareLinkPreview( element ) {
var queryParams, $element = $( element );

// Skip elements with no href attribute. Check first to avoid more expensive checks down the road.
if ( ! element.hasAttribute( 'href' ) ) {
return;
}

// Skip links in admin bar.
if ( $element.closest( '#wpadminbar' ).length ) {
return;
}

// Ignore links with href="#", href="#id", or non-HTTP protocols (e.g. javascript: and mailto:).
if ( '#' === $element.attr( 'href' ).substr( 0, 1 ) || ! /^https?:$/.test( element.protocol ) ) {
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:';
}

// Ignore links with class wp-playlist-caption.
if ( $element.hasClass( 'wp-playlist-caption' ) ) {
return;
}

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.changeset.autosaved ) {
queryParams.customize_autosaved = 'on';
}
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 );
};

/**
* 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.
* @return {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();
}
} );

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';
}

// Amend the post data with the customized values.
if ( options.data ) {
options.data += '&';
} else {
options.data = '';
}
options.data += $.param( {
customized: JSON.stringify( dirtyValues )
} );
}

// Include customized state query params in URL.
queryParams.customize_changeset_uuid = api.settings.changeset.uuid;
if ( api.settings.changeset.autosaved ) {
queryParams.customize_autosaved = 'on';
}
if ( ! api.settings.theme.active ) {
queryParams.customize_theme = api.settings.theme.stylesheet;
}

// Ensure preview nonce is included with every customized request, to allow post data to be read.
queryParams.customize_preview_nonce = api.settings.nonce.preview;

urlParser.search = $.param( queryParams );
options.url = urlParser.href;
};

$.ajaxPrefilter( prefilterAjax );
};

/**
* Inject changeset UUID into forms, allowing preview to persist through submissions.
*
* @since 4.7.0
* @access protected
*
* @return {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.
* @return {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.changeset.autosaved ) {
stateParams.customize_autosaved = 'on';
}
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', 'customize_autosaved' ];

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.
* @return {void}
*/
custom_logo: function( attachmentId ) {
$( 'body' ).toggleClass( 'wp-custom-logo', !! attachmentId );
},

/**
* Preview changes to custom css.
*
* @param {string} value Custom CSS..
* @return {void}
*/
custom_css: function( value ) {
$( '#wp-custom-css' ).text( value );
},

/**
* Preview changes to any of the background settings.
*
* @return {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, handleUpdatedChangesetUuid;

api.settings = window._wpCustomizeSettings;
if ( ! api.settings ) {
return;
}

api.preview = new api.Preview({
url: window.location.href,
channel: api.settings.channel
});

api.addLinkPreviewing();
api.addRequestPreviewing();
api.addFormPreviewing();

/**
* Create/update a setting value.
*
* @param {string} id - Setting ID.
* @param {*} value - Setting value.
* @param {boolean} [createDirty] - Whether to create a setting as dirty. Defaults to false.
*/
setValue = function( id, value, createDirty ) {
var setting = api( id );
if ( setting ) {
setting.set( value );
} else {
createDirty = createDirty || false;
setting = api.create( id, value, {
id: id
} );

// Mark dynamically-created settings as dirty so they will get posted.
if ( createDirty ) {
setting._dirty = true;
}
}
};

api.preview.bind( 'settings', function( values ) {
$.each( values, setValue );
});

api.preview.trigger( 'settings', api.settings.values );

$.each( api.settings._dirty, function( i, id ) {
var setting = api( id );
if ( setting ) {
setting._dirty = true;
}
} );

api.preview.bind( 'setting', function( args ) {
var createDirty = true;
setValue.apply( null, args.concat( createDirty ) );
});

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( 'synced' );
});

api.preview.bind( 'active', function() {
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() );
});

/**
* Handle update to changeset UUID.
*
* @param {string} uuid - UUID.
* @return {void}
*/
handleUpdatedChangesetUuid = function( uuid ) {
api.settings.changeset.uuid = uuid;

// Update UUIDs in links and forms.
$( document.body ).find( 'a[href], area[href]' ).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.preview.bind( 'changeset-uuid', handleUpdatedChangesetUuid );

api.preview.bind( 'saved', function( response ) {
if ( response.next_changeset_uuid ) {
handleUpdatedChangesetUuid( response.next_changeset_uuid );
}
api.trigger( 'saved', response );
} );

// Update the URLs to reflect the fact we've started autosaving.
api.preview.bind( 'autosaving', function() {
if ( api.settings.changeset.autosaved ) {
return;
}

api.settings.changeset.autosaved = true; // Start deferring to any autosave once changeset is updated.

$( document.body ).find( 'a[href], area[href]' ).each( function() {
api.prepareLinkPreview( this );
} );
$( document.body ).find( 'form' ).each( function() {
api.prepareFormPreview( this );
} );
if ( history.replaceState ) {
history.replaceState( currentHistoryState, '', location.href );
}
} );

/*
* 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;
}
} );
} );

api.preview.bind( 'nonce-refresh', function( nonce ) {
$.extend( api.settings.nonce, nonce );
} );

/*
* Send a message to the parent customize frame with a list of which
* 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' );
});
api.preview.bind( 'loading-failed', function () {
$( 'body' ).removeClass( 'wp-customizer-unloading' );
});

/* Custom Backgrounds */
bg = $.map( ['color', 'image', 'preset', 'position_x', 'position_y', 'size', 'repeat', 'attachment'], function( prop ) {
return 'background_' + prop;
} );

api.when.apply( api, bg ).done( function() {
$.each( arguments, function() {
this.bind( api.settingPreviewHandlers.background );
});
});

/**
* Custom Logo
*
* Toggle the wp-custom-logo body class when a logo is added or removed.
*
* @since 4.5.0
*/
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' );
});

})( wp, jQuery );