Get any control/section/panel by passing the id of it.

wp.customize.control( controlId ); wp.customize.section( sectionId ); wp.customize.panel( panelId ); 

Iterate all  panel, sections and controls

wp.customize.panel.each( function ( panel, panelId ) { /* ... */ } ); wp.customize.section.each( function ( section, sectionId ) { /* ... */ } ); wp.customize.control.each( function ( control, controlId ) { /* ... */ …