Add upstream

wp-content/plugins/jetpack/modules/theme-tools/site-logo/js/site-logo.js

@@ -0,0 +1,46 @@
+/**
+ * JS for handling the Site Logo real-time display in the Customizer preview frame.
+ */
+( function( $ ) {
+	var api = wp.customize,
+		$body,
+		$anchor,
+		$logo,
+		size;
+
+	function cacheSelectors() {
+		$body = $( 'body' );
+		$anchor = $( '.site-logo-link' );
+		$logo = $( '.site-logo' );
+		size = $logo.attr( 'data-size' );
+	}
+
+	api( 'site_logo', function( value ) {
+		value.bind( function( newVal ) {
+			// grab selectors the first time through
+			if ( ! $body ) {
+				cacheSelectors();
+			}
+
+			// Let's update our preview logo.
+			if ( newVal && newVal.url ) {
+				// If the source was smaller than the size required by the theme, give the biggest we've got.
+				if ( ! newVal.sizes[ size ] ) {
+					size = 'full';
+				}
+
+				$logo.attr( {
+					height: newVal.sizes[ size ].height,
+					width: newVal.sizes[ size ].width,
+					src: newVal.sizes[ size ].url,
+				} );
+
+				$anchor.show();
+				$body.addClass( 'has-site-logo' );
+			} else {
+				$anchor.hide();
+				$body.removeClass( 'has-site-logo' );
+			}
+		} );
+	} );
+} )( jQuery );